If you’re planning on using Availability Groups in a production environment, I highly recommend you review the following Books Online topic:

Prerequisites, Restrictions, and Recommendations for AlwaysOn Availability Groups (SQL Server)

There are other topics that should be reviewed too, of course, but this particular landing page is being kept up-to-date with various recommended hotfixes,  prerequisite checklists and even information about anticipated thread usage that was originally discussed on the CSS SQL Server Engineers Blog.

Now I’m recommending you keep the online version of this page bookmarked, not the offline version.  If you downloaded the local version of BOL using the Microsoft Help Viewer technique, you don’t have the latest version of the topic (at least I didn’t as of 10/2/2012 and didn’t find a more recent update).  This may get refreshed periodically, but to be safe I recommend you reference the latest version on MSDN and not risk working with stale information.