It seems Windows Phone 8 GDR2 will contain a bit more than Datasense and access to the FM Radio. Microsoft will also be releasing an SDK update for developers, and as we saw earlier today this may expose new APIs which will allow new features to be created.
The news was tweeted by Robert McLaws, a high profile Windows developer.
The SDK and new emulator images briefly became available this morning, but now appears to have been pulled. Hopefully Microsoft has a bit more than expected up its sleeve after waiting so long to release this update.