I googled a bit for free SVN hosting and found XP-Dev.com. After creating my repository I set up XCode to know about my XP-Dev repository. That was a breeze, but then a problem crop up when I wanted to import my existing prototype in the repository. It was complaining about some SCM Error 155007.
Googled a bit more, and luckily some other guys had the same problems. They suggested to do the initial commit from the terminal. This did the trick:
svn import /path/to/project http://email@example.com/svn/
Remember the to do the
To check if it's working fine, you can simply type something in some existing file and save, and you should see an M to the left of the Groups & Files sidebar, meaning it is modified and can then be committed at your will :D