Back in January I had the chance to try out the T-Mobile BlackBerry Curve 8900 and actually bought one for myself and kept it for a couple weeks. If I didn't switch phones so much I would have kept the 8900 because I think it is one of the best overall BlackBerry devices available. It is more compact than the Bold, yet still has a very functional keyboard and incredible display. Today, AT&T announced that they will be bringing the Curve 8900 to AT&T soon.
AT&T also stated that buyers who purchase the Curve 8900 with the unlimited data plan will receive free AT&T WiFi hotspot access in the US. The Curve 8900 on AT&T will also be limited to EDGE data speeds like the T-Mobile variant, but will include WiFi for faster data usage. It looks like AT&T is giving buyers a nice level of choice with the Bold being at the high end with a larger form factor and 3G for data hounds and the Curve 8900 in a more compact form factor with a better camera and higher resolution display. Both are excellent BlackBerry choices.
There is no pricing information available yet for the Curve 8900 on AT&T, but for comparison you can pick this up on T-Mobile for $150 after instant discount and rebate (full price of $500).