I'm a massive Halo fan, and this almost makes me feel a little bit sad. After March 31, Bungie will no longer be looking after your Halo stats, as the transition process from Bungie to 343 Industries will be fully complete.
"Last summer, Bungie and 343 Industries began a transition process for Halo data," reads the update on Bungie's official website. "On March 31st, 2012 that transition process will be complete, all live Halo data will be managed by 343 Industries, and Bungie will no longer be able to update game stats and player service records, to host new user generated content, or to operate the Bungie Pro service. All currently supported, Bungie-developed Halo titles will be impacted by this change."
From April onwards, players should head to http://halo.xbox.com for their stats and info.
I'm almost nostalgic for my old daily visits to Bungie.net. Obsessing over my kill/death ratio, looking for extra info on how close I was to levelling up. I used to keep my laptop open next to me whilst playing Halo 3, watching my stats being uploaded immediately after each match, stalking pro stat. The Bungie weekly update was part of my reading schedule for so long.
Even though I rarely play Halo nowadays, and almost never look online for stat info, it's going to feel weird going to another site for info about the game. Also, this really represents the last vestige of Bungie's involvement with the Halo series they created.