Well its been out with Sprint for a few months already.
Anyone with the original A900 would probably come across some of its numerous bugs.... which the a900m fixes.
Funny thing is that apparently Sprint have been denying its an update but rather a "new phone".
Having said that a certain individual in the US is supplying the flash file and instructions to upgrade an a900 to a900m for US$15.
Felix - any public word on if we are likely to see this update? and if so if Telecom will upgrade customers handsets or expect them to buy a new one?
Edit: The fixes involved include T9, GPS, bluetooth and now includes downloadable themes.