I'm not a fan of retesting new drivers, especially with the almost regular monthly schedule of ATI's driver releases. But in this case I think Anandtech should do a retest. I've always felt looking at the numbers that there was more performance to be had from the Radeon 5xxx series and that immature drivers were holding it back and to a degree. Preliminary buzz seems to be that these drivers improve performance but I'd love to see what it does in a full battery of tests.
Xbitlabs does every month or two (usually) and a handful of games, less than half a dozen, over a few cards (including Crossfire).
It's quite nice to get an indication of changes, and especially if the drivers claim specific speedups, to test them out.
With the HD57xx cards it really is quite important to retest with updated drivers, because conclusions were made that they don't offer a reasonable alternative to the HD48xx cards, and with driver speedups that conclusion could change.
For the HD58xx cards it's not such a major issue, they are already the fastest single cards, but again for Crossfire (HD5970 and crossfired anything) it could have a more significant impact.