yes, its not only free, but open source.

http://vimeo.com/1221926

Does anyone know what I have to do that the sculpting mode work?
increase the multires and 'drawing' on the mesh with the LMB doesn't result in anything! There must be a special trick. And I don't see that I do anything different to the explanations and videos that I found. Thanks!

you have to switch from object mode to sculpt mode.

I actually did. The reason must another one.

What I did in detail:
- I tried it with different versions of blender on a Windows XP machine
- I chose sculpt mode
- I chose different sculpt tools like draw, pinch, grab
- I changed the values of strength and size
- I tried it with the default cube, with multires set to different levels
- I tried it with an imported obj file with different settings of level of multires

I hope it is something obvious - that I certainly never forget when someone points it out once...

The sculpt mode ( the feature that I really need) made my pc crhashed.
AppName: blender.exe AppVer: 0.0.0.0 ModName: atioglxx.dll
ModVer: 6.14.10.7873 Offset: 0046b200

I am looking for the previous version but I can't find it

Shxx , even the 2,47 won't works!

Tried it on my laptop and it runs fine!
Now, my guess is that its because of my graphic drivers.
I'll have a look into this!

An update of the graphic drivers did the job.
It works now.
Thank you for your patience.