I'm working on a VM/ec2 image for Gitorious to ease the installation pain. I'm working from the the Ubuntu installation script that the Gitorious project provides, and I will try to get the improvements merged upstream. Things are mostly working, so I will be making the work public after a few more days of testing. Feel free to contact me if you'd like more info.
I don't know, the only problem I found so far is the lack of tag display.
It is a bit harder to install than gitosis, but you also get much more (for example, people can create projects and repos without your help, all the visual stuff, etc..)