I was in the market for a Google Analytics plugin to track individual domains on a WordPress Multisite installation under a single Google Analytics Profile.
There is a current maintained plugin for this called Google Analytics MU.
This is a fork of a more well represented plugin (in the search engine results) called Google Analytics Multisite Async which was last updated 2011-2-8. The author of the Google Analytics MU plugin noted he forked it because the developer of the Google Analytics Multisite Async was unavailable, which I also found to be the case when trying to content the plugin author.
You’ll want to install Google Analytics MU and “Network Activate”. Configure the settings and you’re ready to go.