It seems that the Xperia X10 may never get its Android 2.1 upgrade for AT&T users. The model was released last year by the mobile network running on Android 1.6; however they promised that an update would soon follow. That promise might not see the light of day as the company no longer sells brand new Xperia X10 models.

Despite the bad press surrounding the Xperia X10 and it’s outdated version of Android 1.6, Sony Ericsson still released the Xperia X8 with Android 1.6 instead of 2.1. The company did however promise an update to Android 2.1 for the Xperia X8, along with the Xperia X10 range. Sunday saw the first Android 2.1 kits go out for the Xperia X10 range, with other kits/markets following through the month. However Xperia X8 owners were told that the planned update would fall at a later date than the X10 range, despite the software being the same as that used on the X10 Mini/Mini Pro, with the use of the four corner shortcuts.

While we’ve already seen the Xperia X8 here in the UK, Sony Ericsson have just announced that the “medium sized X10″ is now shipping worldwide. However comments from Rikard Skogberg indicate that although the handset is now shipping, not all markets or networks will release the handset immediately. It was hinted at that some markets may wait to release the Android powered handset until the 2.1 update is released for it. We already know Android 2.1 has been delayed for the Xperia X10 range. Unfortunately the Android 2.1 update will be released slightly later for the X8.

When TweetDeck was released in Beta a month or so ago, many Android users rejoiced as it’s one of the most popular iPhone Twitter clients. Xperia X10 owners couldn’t join in the celebrations though, as the Beta was released for Android 2.0 and above. At the time, the creators of TweetDeck said that while the beta will only support 2.0 and above, the final version should be able to support lower versions of Android.