Audi will be blowing out the "B7" versions of the A4 straight through to September when the newly revised 2009 "B8" version of A4 will go on sale.
The B8 is going to be a significant revision, with completely new transaxle/transmission configuration that will put the engine 6 inches further back behind the front axle. Weight distribution (especially on the 2.0T) will be much better, and so will handling. The 2.0T also has a redesigned engine, and with a 50ft-lb boost in torque. It should perform quite well compared to the 328xi/328i that it is targeted to compete against.
The current A4's aren't bad, but the expectations for the new A4 are pretty high. So prices of the current A4 will probably trend lower as more Audi enthusiasts wait out the arrival of the new re-design.