A tiny bit of uncertainty has been cleared away thanks to good old Twitter, where T-Mobile has made July 15 (aka, today!) the official launch date for its Galaxy S derivative, the Vibrant. The original Tweet seems to have disappeared into the ether apart from that screenshot above, but T-Mo has reiterated the statement in subsequent missives, telling its followers that the Vibrant will be on sale today. We imagine the typical $199.99