Maybe this is helpful to others trying it as well:
I just checked out the current version from svn.
There is packages/projects/visualstudio_2010, which has a build.sln for vs9 but several vcxproj files for vs10 in it. Because of that, it says some projects are missing when opening it with vs10.
There is packages/projects/visualstudio_2008, which has all the things for vs9 and I can convert it myself to vs10 so it loads correctly. However, the core project in that solution uses the files from core200, so I assume that's not the way to build 300.
Then there is /coreLibrary_300/projets/windows/project_vs2010. Trying to build it in releaseDLL leads to an error: LINK : fatal error LNK1181: cannot open input file 'C:\meinedat\projects\Newton\3.00Alpha1\newton-dynamics-read-only\coreLibrary_300\projets\windows\project_vs2010\Win32\physics\debug\physics_d.lib' Maybe this should be physics.lib Building it as release works.