AT&T is doing some big network upgrades. The current 3G cap on the AT&T network is 3.6 megabits per second - that'd be increasing to 7.2 Mb/s. They're doing software upgrades at all the base stations to get this boost.
HSPA (the technology behind AT&T's "3G" network) can be pushed to 14.4 MB/s - but due to technical issues and the readiness of HSPA+ (call it 4G), AT&T will be skipping over that upgrade to move their network to full on 4G HSPA+ later this year. That's speeds of up to 21 Mb/s, nearly 6 times what they've currently got.
This could be the "significantly faster internet speeds" rumored to be coming on the new iPhones rolling out this June.
http://www.modmyi.com/forums/iphone-...ling-soon.html