CM7 isn't out, and if it is it's not for the Droid. Last I heard the CM7 code was functional, mostly, barely, and it had no optimizations.
CM 7? Well, for starters, It's just basic Gingerbread. No optimizations and all the problems every other D1 Gingerbread ROM is having, including reduced Market functionality.
The latest nightly is only two days removed from 6.1.2 and has the rotary lockscreen if you're interested.
The purpose of this thread was to prevent people from continuing to install 6.1 RCs and whatnot because they didn't know where to look to get the latest version. When the CM 7 nightlies start dropping they'll drop on the repository so it's a good idea to go check every few days.
No wipe needed between minor update -- 6.0 to 6.1, for example. I flashed the latest nightly over my 6.1.2 install without any problems. All you'll need to do is reinstall any custom kernel you might have been running if you were running one.