The Adobe Mobile Packager installs Flash Lite 3.1 player when needed.
But what is exactly FL3.1 ? a special version for AMP or a new Flash Lite, with new API and class.
Adobe release a document in its Mobile & Devices Developer Center which gives, with a very handy way to check each version API, some answers : ActionScript Support for Flash Lite and Adobe Mobile Client.
It's interesting to see BitmapData (and linking class like ColorTransform, etc...) are now here. I make some experiment in Flash with BitmapData and I really like to use it for tile-based games !
Rectangle and Point will increase the available AS2 components which can be converted to FLite.
You'll also find ExternalInterface and LocalConnection are here in Flash Lite 3.1.7... what the hell is 3.1.7 !?! :)
And before you ask, like I did, what AMC is, check this post from Scott Janousek