Sony Xperia X10Fans of Sony Ericsson’s phones have been waiting for the release of its Xperia X10 Android smartphone since it was first announced last fall. Today the company officially announced that the X10 will be hitting AT&T on August 15 for $149.99 with a two-year contract, reports Engadget.

Sony says that it will be $20 less at its Sony Style stores, and in a week it will be a mere $49.99 with a contract at Amazon.

But don’t start celebrating yet. For some inexplicable reason, the phone will be running Android 1.6 when it launches — even though most new Android phones are packing the faster and more polished Android 2.1 these days.

That the X10 is running a seemingly ancient version of Android (by mobile OS standards) will be a major knock against the device, which was initially supposed to be Sony’s flagship Android device. It still packs some decent hardware with its 1-gigahertz Snapdragon processor, 4-inch touchscreen, 8.1-megapixel camera, and 8-gigabytes of on-board memory (plus a 2GB memory card) — but that power won’t be fully tapped until the X10 gets upgraded to a newer Android OS.

The phone runs Sony Ericsson’s own apps on top of Android — Mediascape and Timescape — which offer integrated social media and other media experiences. Ericsson’s apps certainly help to differentiate the phone against the onslaught of look-alike Android devices, but they are likely also the reason that the phone is stuck with Android 1.6. Ericsson has been hard at work at its custom user-interface for some time, and it likely couldn’t keep up with Android 2.0 releases in time for its launch.

I wouldn’t write the phone off entirely, however. When the X10 does get upgraded, it will be an interesting, and surprisingly affordable, Android entry.