While browsing a repository on a custom hostname ( http://code.yogipatel.net/test ), the username link links to the repository URL, not the user.
For example, at the above URL, the path shown in the header is "yogi / test". test links to the repo correctly. yogi links to the repo as well though — not the user profile page (which should be http://code.yogipatel.net ).
If it's possible to see BitBucket's source and submit patches, I wouldn't mind fixing this for us :)
Wouldn't mind adding GitHub style project pages / CNAME support either (though that is certainly less trivial).