Well, I totally blew this one I missed a conditional compilation line the tool for VS2010 and it is looking in the VS2008 registry location. I tested a clean VS2010 install from setup, but unfortunately had a VS2008 installation there as well, so I didn't see the problem.
For a quick fix, try the following from a command prompt opened with administrator permissions (you can put these lines in a .bat file if you like):
reg save "HKLM\Software\ORM Solutions\Natural ORM Architect for Visual Studio 2010" generators.hiv
reg add "HKLM\Software\ORM Solutions\Natural ORM Architect for Visual Studio 20008"
reg restore "HKLM\Software\ORM Solutions\Natural ORM Architect for Visual Studio 2008" generators.hiv
If you have VS2008 in a side-by-side install you should not do this (the reg add and reg restore lines will fail). For a 64-bit machine, you'll need to add \Wow6432Node to the registry keys immediately after Software.
You should now be able to restart and see the generators. My apologies for the inconvenience. I'll try to get an official fix out for this and a handful of other VS2010 issues in a couple of weeks, but I'm pretty slammed right now. VS2010 was a major set of changes (585 files across 4 repositories), so please be patient while I work out the remaining glitches.
Let me know if this enables your generators correctly.