It's not exactly groundbreaking, but Facebook 1.5 for Android has launched, allowing some Android users to play catch-up with their iPhone-loving buddies.The update brings two key features to Android phones - push notifications and chat. But there's a catch. The update is only good to go for Android 2.2 users, which is less than half of total users right now. So it's an update, but far from universal.If you are a 2.2 user, head over to the Android marketplace now to enjoy the full chat mode (with background notifications) and those push notifications. Not push notifications for everything though. According to TechRadar, the only notifications on offer relate to chat and not to comments, likes or anything else you know, love and use on Facebook. Still it is a free update and we suspect, a welcome one, despite its limitations.