The Windows Phone 7 update screen.

Good news for those who were worried about getting bottlenecked roll-outs of system software updates on Windows Phone 7 devices: Microsoft, and not the carriers or the device manufacturers, will be in charge of that duty.

In an e-mail exchange with ZDnet, Microsoft reiterated that it will "push Windows Phone 7 software updates to end users," while adding that "all Windows Phone 7 devices will be eligible for updates." These are two very big things that bode well for early adopters of the handset, but also put pressure on Microsoft to keep that promise as the Windows Phone platform ages.

Microsoft's position is of special interest given the current climate of smartphones system software updates, which up until a few years ago had been either few and far between or nonexistent.

To put the current update landscape in perspective, Apple pushes out what has become an annual update directly to iPhone owners through its iTunes software, instead of through over-the-air carrier updates. Though with its latest OS update, Apple began limiting what features would be available on older models, and even cutting out the original iPhone from getting the newer software.

Apple's cycle could be considered generous when compared to Google, which came under fire during most of 2010 for its Android update strategy. Unlike Apple, and now Microsoft, Google has mostly gone through the carriers and device manufacturers to deliver over-the-air software updates. This has led to some considerable delays in getting version 2.2 of its operating system out to users who may have purchased new phones just a few months after the software was released.

There's also the continuing march of Android hardware requirements for each OS iteration, which has left large groups of early adopters unable to get even parts of the updates. RIM faces similar timing challenges in rolling out the sixth version of its OS to BlackBerry users.

Of course the bigger question is how long Microsoft will have to keep up this promise of offering software updates to Windows Phone 7 users as the platform ages. Given what's happened with competitors, it's fair to expect that new features that require additional hardware adjustments simply get saved for the next major version of the OS. But even there, that could get a little sticky given the pace at which new phone hardware is released. And it could end up leaving some wiggle room akin to what we've seen on the PC side for buyers to pick up "Windows Phone next"-ready devices that would be eligible--and more importantly, capable, of the next major upgrade.