Let's put aside the folks who dinged 85 in under 18 hours and just focus on normal leveling attempts from 80-85.
Got on tonight, did the basic stuff on all my 80s (got old world flying, upgraded tradeskills, etc) and was just getting ready to enjoy some fishing and cooking with my main when a buddy logged in and wanted to run a new instance - NP - don't get to group with him often and I was curious anyway.
We ended up running Blackrock three times as the toys were dropping fast and furious and I just couldn't resist trying for some boss drops for my druid.
Those three runs, combined with the quests inside, doing fishing and cooking as well as the quest that's pretty much forced on you as soon as you log in got me about 3/4 the way to 81 and that's with only (assuming rested started at 3am my time when Cata officially launched) about 15 hours rested XP under my belt.
I'm sorry, that's ridiculous.
My gal was up all night (with about four hours worth of cat naps throughout last night and today) and alternating between leveling and working archeology. She was with us for the three instance runs and she's at 82 now.
Also ridiculous, especially seeing as how she was taking her time, smelling the roses and flying around seeing/exploring stuff in the process.
Guildies who've been working alts report that level advancement is just as obscene at the lower levels, especially with heirloom gear - with rested and a full heirloom set they pretty much just have to park their toons in front of the mailbox for ten minutes and the toon will ding just standing there doing nothing.
I don't mind pointless time sinks being removed and I'm certainly not asking for the bad old days of EQ where you lost XP when you died and it took a five man group to take down an even level mob, but come on, this is ridiculous - with these XP advancement rates I'll be able to get all six of my 80s to 85 before the end of the year and then what - level my bank toon to 85 to kill time?
I'm sorry, but while I'm sure the ADD crowd is thrilled that they're now able to get a level just from staring intensely at a random mob...basically, I'm not asking for every level to take weeks to get like EQ did back in the day, but I'd really like to have it last a bit longer then an hour or two like WoW is now.