How’s this for some swagger? Bellevue-based T-Mobile USA plans to offer a $1,000 prize to anyone in the Seattle area whose iPhone can beat its Galaxy S 4G smartphone in a download speed test this weekend.

It’s a publicity stunt, for sure, but it’s also an interesting public display of confidence in the device and the company’s HSPA+ network vs. the iPhone running on Verizon or AT&T (which, of course, is in the process of buying T-Mobile USA).

The tests will take place in T-Mobile retail stores, using a third-party speed test application, in a best-of-three trial. Just so you don’t get your hopes up, the HSPA+ network has a theoretical peak download speed of 21 Mbps. But hey, for $1,000, it’s worth a shot.

The promotion — in the Seattle area only, for now — starts Friday and runs through Sunday at 10 T-Mobile retail locations in the region, including downtown Seattle (1527 6th Ave.), Bellevue Square, Northgate Mall and seven others.