The question is "How to Allow Two Developers Access to a Plugin on the WordPress.org Plugin Repository?" This question was asked on the wp-hackers list and @EAMann answered it nicely and it's a great question to have here so I'm posting it for Eric to answer here.
There are two (2) steps.
Add the WordPress.org username of the contributor you want to add to the "contributors" line in the header info of the Readme file, and that person will have SVN commit access to the plugin.
Go to the plugin repository and log in with the main account
- Go to your plug-in and click the "admin" tab
- Add the user's WordPress login name to the list of committers by entering their name and clicking "Add Committer."