This rumor just won't die, no matter how many times people try to kill it. And it seems that no one is satisfied to just wait and see when Halo 2 shows up, they've got to be speculating that something big is happening on the 15th to mark the two-year anniversary of Halo and the Xbox-- besides the DVD controller with extras that's already been mentioned.
This time, it's the revival of the "Halo 1.5" or "Halo Gold" or "Halo Online" version that was widely rumored to be following the initial version of Halo, motivated mostly by players disappointed that Halo didn't work on XBL. (Nevermind that Halo was being finished before the XBL API had even been published fully to developers... developers... developers.)
Bungie's own Matt Soell (now departed) squashed this rumor flat in the Rumor Control Database, saying: "We will not release a Halo game with explicit support for the Xbox Live network until Halo 2 ships." That's pretty unambiguous.
However, fueled by mention of a "Prima Guides Halo Deluxe Edition" (gee, think that could be the Deluxe Edition of the Strategy Guide, not of Halo? Maybe) several sites have gone right off the deep end.
But after SketchFactor killed the recent rumor that Halo 2 had been finished in secret and was ready for a Nov 15 release, it looks like the rumormongers came back to this dead horse and decided to take a few more whacks, which of course got mentioned even in places where they know better. In fact, some stories used SketchFactor's denial as evidence that Halo Deluxe exists.
Or, of course, Bungie changed their minds. Whichever.