Here's a more or less simple way to migrate from Subversion to GIT(hub), this includes mapping commits and tags and what not!
Authors
If multiple people congtributed to your project, this is probably the toughest part.
If you're not migration from let's say Google Code but PHP's Subversion repository, then it's really pretty simple indeed: the username is the email address.
I found a nifty bash script to get it done (and adjusted it a little bit):
