v1.0 of SPG Mobile App on iTunes as of 6/6/09 (iPhone app)
One of my favorite Starwood'ers gave me a tip: v1.0 of the SPG Mobile App is available on iTunes!
I know the SPG team is anxious to hear everyone's feedback and will be watching this thread for everyone's comments.
It says you can check your SPG balance, upcoming stays, and even map from your current location to the hotel! It also says you can search and book from the app, with links to global customer support. Sounds cool.
It's free so anyone with a iPhone or Touch should get it and check it out.