Bungie.net news update brought with it more than just info about Halo: Reach's Xbox Live stats -- it also featured a couple of screens showing an extra 10 Achievements and 250 Gamerscore for the just released title. In a segment explaining how to install the game to the 360's hard drive, two screens can be clearly seen with the adjusted Gamerscore and 'Cheevo count (1250 up from 1000 Gamerscore and 59 up from 49 Achievements).
Bungie doesn't directly address the changes in its update, instead hinting at "some new stuff" being added in a "potential second October update." Unfortunately, this hint is dropped right after talk of the regular housekeeping performed on Halo multiplayer, so it's unclear what's being hinted at directly. Halo 3 was eventually lavished with an astonishing 1750 Gamerscore when all was said and done, so the idea of an extra 250 doesn't seem like much of a reach if you ask us.
[Thanks to everyone who sent this in!]