The scene yesterday evening at the downtown San Francisco Apple store.

If there were any lingering doubts that Apple's iPad sequel would draw the same interest the first-generation device did, they were quashed before stores even opened their doors yesterday.

The iPad 2, a device that was unveiled just 10 days ago, launched to huge crowds and inventory that sold out quickly, both in stores and online.

Shipping times for online orders, which opened yesterday morning at 1 a.m. PT--some 16 hours before the first Apple retail stores began selling the iPad 2--were quickly pushed from days into weeks. This left the best chance for customers who wanted to pick up a device before April being to head to one of Apple's stores, or its partner retailers such as Best Buy, Target, Wal-Mart, and carrier stores for Verizon and AT&T.

Analysts like Piper Jaffray's Gene Munster are already setting estimates for first day sales somewhere between 400,000 to 500,000 units, some 200,000 better than the first iPad did during the same time period in its launch. Apple is expected to unveil preliminary unit sales on Monday, as it did on the Monday following the launch of the first iPad.

Big numbers Until those numbers come in, there are some signs this launch is off to a bigger start than that of the first-generation device. At Apple's flagship store in San Francisco for instance, which CNET was monitoring along with stores in Manhattan, the line practically ran out of room, as it wrapped almost around the city block. That store sold out of its entire stock of Wi-Fi-only units just a few hours after iPad 2 sales began, leaving evening line-waiters with only the option of buying the more expensive models with 3G service from Verizon. Worth noting is that this is the same store that had the richest supply of iPads following last year's shortages.

It was the same story on the other side of the country, with the line outside New York's Fifth Avenue store growing to an estimated 800 people, with some having begun waiting in line on Wednesday night and braving torrential downpours. For one individual, that perseverance--as well as her spot at the front of the line--netted her $900 from someone else who didn't want to queue up.

At least 200 people line up outside the Apple store on the Upper West Side of Manhattan yesterday, waiting for the iPad 2 to be released.

As with previous Apple launches, the art of the line wait has become a business. The first two spots at the San Francisco store went to "runners" for TaskRabbit, a service that specializes in sourcing out errands and other odd jobs to its workforce of vetted contractors. James Alimeda and Josh Elavitti were paid $60 per iPad they were waiting in line for, with each buying two. In Alimeda's case, he was already there to purchase one for himself. Those two, along with two others in line, were part of a much larger operation at various retailers to help people procure devices without putting in line time.

Behind them was a group of around 35 non-English speaking line-waiters who managed to get an Apple store employee who could speak Cantonese to act as a translator, just a half-hour before iPad 2 sales began. According to a report on Bloomberg, their aim was to buy iPad 2s, all going to one single unidentified buyer, who planned to sell them on the gray market, likely at a premium and in places where the device was not yet available.

Speaking of which, the iPad 2 goes on sale in 26 additional countries just two weeks from now, arguably giving gray market buyers from those areas less of an incentive to deal with international travel. However, given some of the initial demand from this first day, there's the possibility that Apple could once again decide to push that launch back, as it did for the first-generation device.

The device Of course, why people were lining up in the first place is always on the minds of passers-by. One woman who walked past the line asked if there was someone famous playing a show there that evening. Others were seeing the device for the first time in an iPad 2 demo video Apple played in its retail store display.

The iPad 2, which CNET has given a four-star rating in its review, is a refinement of the the first-generation device. It's thinner, it's got a faster processor and better graphics chops, and it's the same price. It's also got new features like dual video cameras and compatibility with new accessories like a neat cover that attaches to it with magnets and an AV cable that can mirror whatever you're doing onscreen to anything with an HDMI plug.

For many buyers though, this second-generation device is something they were waiting for before pulling the trigger on the original iPad. That's what many buyers CNET talked to mentioned as being one of the big attractors. They know Apple's cyclical product release schedule by now and were counting on a refresh of a few key things, even if they didn't necessarily need them.

There are things Apple could have added, but didn't. Though with lines like this on opening day, it seems the revamp offers enough.

End of the line As is the question every time Apple sells a product with this much fanfare, why is there this big rush to get it on opening day And why can't Apple seem to meet demand when this happens again and again With the first iPad, this was easier to answer. It was a new product, in what had so far been a niche category. Apple seemingly didn't anticipate the demand, and thus was forced to play catch-up as it went on to make its way to a million units sold in under a month's time.

This time around, however, Apple's got more retail stores, and a handful of retail partners on board to get what is likely to be more units out the door in a shorter amount of time. The original iPad has also proved to be an overwhelming success, with Apple selling more than 15 million of the devices.

Even so, Apple had very subtly reconfigured its launch plans with this one to encourage people to buy the device in person, doing new things like keeping online purchases from starting until the day it went on sale, while throwing in the usual mix of temptations for buyers to come to its own stores, with food and drink for the wait in line and personalized setup (the free service that has retail employees getting new iPads up and running before buyers leave the store--an important step considering the iPad, like the iPod Touch, first needs to be activated with iTunes before buyers can begin using it.

The simplest answer to the mad rush, though, continues to be Apple's terrific marketing--one of the many things that separates Apple and its products from its competitors. For many who go through the wait, it's not just about the device, it's the experience that happens before they even break out their credit card, something that's hard to put a price tag on.