Andy Rubin, leader of Google&39's Android project, speaks to reporters at Google I/O.

SAN FRANCISCO--Android, Google's top developer priority, hogged the spotlight at Google I/O today--in part as the foundation for new Google music and video services.

Among the Google I/O announcements today:

&149' Google announced Android 3.1, an update to Honeycomb that adds new interface options, lets people plug in USB devices, and sports a movie rental service that works directly from the device. Android 3.1 comes to Motorola Xoom owners today and other tablets later.

&149' After Honeycomb comes Ice Cream Sandwich in the fourth quarter, which incorporates Honeycomb features but works on phones and Google TV devices as well. Job No. 1 for Ice Cream Sandwich is reducing the fragmentation problem that makes it hard to write one Android app that works on multiple devices, but Google was cagey on new features coming to make that possible. Also coming with Ice Cream Sandwich is a facial tracking technology.

&149' Google's cloud-based music streaming service arrived, as expected. With it, people can upload their own music collection and stream it to their devices--including to new Android-powered Project Tungsten devices that send music to a person's home stereo system. The service is in invitation-only beta right now in the United States. For a look, check out CNET's Google music slideshow.

&149' The Android 3.1 update to Honeycomb comes with a movie rental service, including the ability to browse and rent movies directly from a tablet and to cache the movies for watching even if there's no network connection. When people rent a movie, they have to watch it within 30 days, but once they actually start watching it, they have 24 hours to finish. The service begins in the United States but will eventually be launched internationally.

&149' Google and Samsung gave away 5,000 Galaxy 10.1 tablets to Google I/O attendees. Honeycomb apps are the company's top developer priority, said Android leader Andy Rubin.

&149' Google wants Android to be the hub for any number of devices--home lighting systems, dishwashers, exercise bikes, and more. In addition, Honeycomb tablets running Android 3.1 will act as USB hubs so keyboards and cameras can be attached.

&149' Google has some big numbers reflecting Android adoption, including 100 million Android devices activated, 310 devices on sale so far, and 4.5 billion app downloads to date.

&149' Google says people will be able to customize their own hardware accessories to be controlled via Android, through its Android Open Accessory initiative and the Android Device Kit, which is built on the open-source Arduino. No release date or pricing has yet been announced for the SDK.