UPDATE MARCH 25 20:20
According to the Xbox support web site, all Xbox services are up and back to normal. Hopefully if you were affected by today's issues, you're still able to get in and play some Titanfall or Forza 5 tonight.
The original story appears below
Earlier today, some users were experiencing issues with Xbox Live services related to reported "scheduled maintenance," but new issues have sprung pointing at a possibly larger problem. While the maintenance primarily affected the online experience with Forza 5, issues now extend to Titanfall, Modern Warfare 3, and Halo 4.
As of 3:49:39 PM CST, Microsoft wrote on their official Xbox support site: "Are you running into connectivity issues when trying to play Titanfall or Forza 5? Are you having issues when trying to purchase in-game content bundles for Call of Duty: Modern Warfare 3, Fable Trilogy, Twisted Pixel, and Halo 4? Our team is engaged and working hard to get these issue resolved as quickly as possible. We appreciate your patience while our engineers investigate. Check back for an update in 30 minutes."
Microsoft says that users may experience issues:
Accessing all game features
Accessing or retrieving data stored using cloud storage
Capturing game videos
Joining other Xbox Live members in online games
Posting game performance or viewing the performance of other Xbox Live members
Purchasing content bundles
We'll update this story as it develops, but Titanfall's servers are currently offline and unavailable in the GameSpot office.