Have been running Win 7 RC x64 for approx. a month now, did a clean install. My main photo tools run without problems, I use CS4, LR2.4, Downloader Pro v2.2.4, GeoSetter, Color Eyes Pro v1.5.2, Spyder 2 puk, even the seldom used Canon DPP software is running OK.
Actually have I only had one software issue and this where with installing the HP B9180 printer drivers, as the HP setup program refuses to install under Win 7, but doing a normal Windows install of a new network printer (I'm running the B9180 on the Ethernet) and then point to the unpacked HP drivers folder did install all the necessary printer drivers and profiles. I have been printing from LR2.4 without problems after this printer install method. The various HP tools for the printer supervision do not work, but no big issue in that.
My only problem have been with the Intel Matrix Raid driver v8.9 as these seams to randomly drop a drive, solved by down grading to v8.7 (some folks can also get v8.8 to work). There is a lengthy history on this on the Intel Forum and it seams not to be only a issue with Win 7, but looks like other Windows OS also are bit by that error when running newest v8.9.
/Bo
Btw. If you do have stored your raw files and/or Lightroom library under the main My Pictures folder, then beware that every time you start the Media Player it rescan all folders contained in My Pictures, it can get LR quite jumpy if your running LR at the same time as the scan is going on . There seams to be no way of stopping this behavior from within the Media Player. So move your raw pictures and/or LR library out from the My Pictures folder.