Eclipse Indigo + M2Eclipse 1.0 makes it very easy.
If you don't already have the Git connector for M2Eclipse install it. M2Eclipse will help you along by prompting you on the Import menu.
- Select the "Import..." context menu from the Package Explorer view
- Select "Check out Maven projects from SCM" option under the Maven category
- On the window that is presented choose the link "Find more SCM connectors in the m2e Marketplace
- Find connector for Git...install...restart
Note that in the search box you may have to enter "EGit" instead of "Git" to find the right connector.
With that done, simply go to the EGit repository, bring up the context menu for the Working directory and select "Import Maven projects...".