The long-expected update to the Android operating system, version 1.5, has arrived. T-Mobile will be rolling out the new OS to existing G1 phones starting sometime next week. While you wait for your share of the software upgrade, take heart: There's plenty to be excited about in the 1.5 release.

The final release of the Android 1.5 OS, previously known as "Cupcake," finally brings an on-screen virtual keyboard with vibration feedback, plus video recording, playback, and sharing via YouTube. T-Mobile is expected to roll out this update to all its G1 customers by the end of the month.

Cupcake also brings many user interface refinements, along with accelerometer-based application rotations. The home screen now features widgets as well; some of the bundled ones include a calendar, an analog clock, music player, and search (with improved voice search).

G1's browser is up for a treat also, with new copy and paste, search within a page, tabbed bookmarks, and history features. Wireless music fans will appreciate their G1 even more with A2DP stereo Bluetooth support (iPhone users -- hang on, you're getting this in 3.0 also) while auto-pairing was added with an improved hands-free experience.

Gmail on the G1 gets upgraded with batch editing functionality for archives, labels, and deleting. The contacts app will now show user pictures for your favorites and specific date and time stamps for events in the call log.

Google has put up a presentation video (below) of the Android 1.5 release. It's worth noting that the engineer showcases the new Android 1.5 features on the G2 (HTC Magic), which is available only in Europe at the moment on Vodafone. The European G2 doesn't have a physical keyboard and comes with a 3.2-megapixel camera (same as the G1).

With the Android 1.5 release, Google has caught up with the features expected to come from its main rivals this summer -- the iPhone 3.0 update and Palm's WebOS. All in all, it's nice to see that Google approached the same strategy as Apple when it comes to upgrading a phone's features without making the hardware obsolete (unlike, ahem, Nokia).

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