Super-guild has already cleared Naxx

[Skandranon]

It's not really all that surprising considering Skan got first level 80 mage and human on Stormrage in about 60 hours real life time with a sleep break in there somewhere (he hit 80 right around Noon time on Saturday, maybe an hour or two later). If you know what to do and where to do it, getting to 80 quickly isn't difficult. I should hit 80 Wednesday night with Tahapenes and that's with probably around 65 to 70ish hours played since Wrath launched.

Something also to note was that I delayed my final level up by around two hours so that Heda could catch up and we could both get first human to 80 (there's a one-minute window after any realm first is achieved - anyone meeting the requirements in that minute is also awarded the first). I also could have shaved another three to four hours off my time if I'd had as much experience with Icecrown and Storm Peaks as I'd had with all the other zones - they were closed on beta when I did my leveling up there, and I never really got back to check them out. So my last level and a half was done with some fairly inefficient questing, as well.