My team has just started looking for a github replacement because the code review workflow is just not working for us, we need something with more structure. I think there's plenty of space for feature and price competition, especially for private repos where github's social network effects don't matter as much.
We use gerrit hosted on EC2 mirroring commits to github for backup.
the only thing I've found missing is the ability to render images inline. If someone submits a documentation update with SVG and PNG updates, you have to download the changeset to see the files. It would be nice if an option for "view this attachment inline" were available without installing extensions.