Microsoft's Press Release: While the feel of this new chapter greatly resembles that of previous Halo experiences, Halo 3: Recon will require you to employ more elements of stealth and cunning than ever before.
The word "stealth" here isn't really a great word. This isn't a stealth action game like a Splinter Cell game. This is a Bungie-made Halo game where you will play as an ODST, which of course, is different (and no, I'm not talking about how it's different ;b) than playing as a Spartan super soldier. This isn't Halo Cell, Ghost Recon: Halo, Republic Commandalo or whatever.
Edit: Forgot Call of Halo and Gears of Halo.