SCOTUS Blog has details about the litigation and will post the audio of the arguments as soon as it becomes available. Due to the importance of the cases, the Court will release the audio shortly after the arguments conclude. Start with the links here, and check the main page for updates.
Other helpful posts & sites are:
Marty Lederman at Balkinization. Keep an eye on the main Balkinization page after the arguments are over.
On-line debate sponsored by the Federalist Society.
The ACLU position outlined at the American Constitution Society Blog.
Michael Dorf on suicides at Gitmo.