If you're an English-speaking XP user then IE 7 is now "gold" and out of beta testing.As a developer it's your duty to get yourself a copy and test your sites in it to see if you're ready.
Unlike previous releases, version 7 is to be shipped to users via Windows automatic update. When this starts happening you can expect a steady trickle of complaints from users if your sites aren't fixed by then.
As a developer I plan to keep my main development PC on IE 6 for a while. To do this I am going to tell it not to allow the auto-update to IE7. Instead I'll install version 7 in Parallels and test there. At some point I'll switch that round and develop in 7, while testing in 6.
Anyway. Onwards and upwards. IE 7 is a massive step in the right direction and feels like a really solid browser to me. Hopefully soon we won't need to worry about IE5.5 any longer.
Remember. Find the bugs before your users do!