As noted on the XNA Game Studio team blog and this App Hub news item, the deadline for submitting Xbox LIVE Indie Games created with XNA Game Studio 3.1 to play-testing or peer review is only one week away.  Here are the key things to keep in mind:

• Starting at 12am PST on February 8, 2011, you will no longer be able to submit Xbox LIVE Indie Games created with XNA Game Studio 3.1 for play-testing or peer review, and instead you must use XNA Game Studio 4.0.  This includes updates to previously published games.
  
• If your game is in peer review by 12am PST on February 8, 2011, it will be allowed to complete the peer review process.  If it passes peer review, it will be published to the Xbox LIVE Indie Games marketplace.  If it fails peer review, you will have to upgrade it to XNA Game Studio 4.0 before you will be able to re-submit it.
  
• If you have previously published an XNA Game Studio 3.0 or 3.1 game to the Xbox LIVE Indie Games marketplace, it will continue to work correctly.  You do not have to upgrade it to XNA Game Studio 4.0 unless you plan to release an update after 12am PST on February 8, 2011.
  
• You can still deploy and debug XNA Game Studio 3.1 games on your Xbox 360 console using XNA Game Studio Connect after 12am PST on February 8, 2011.  This deadline only impacts 3.1 games that you plan to submit for play-testing or peer review.