Since two weeks i also have a G15 keyboard and i like it.
It is possible to get the latest X messages sent & received on msn. For the sign in information, i think you can get it trough the MSN api in combination with the SDK from Logitech (you can create your own dll)..
Or.... Maybe even cooler, a WLM plugin (since WLM supports plugins) combined with the SDK kit.
When i have time i might have a look at it but don't get your hopes up...
/ 
