if you're alliance..you can maybe AFK...but you have to watch it as there've been a decent amount of bans on LK profiles.
for horde, absolutely not...not right now, anyway...there are no profiles that are stable/complete enough.
i did archy 70-75-ish, then gathering in icecrown/stormpeaks to about 78, then gathering in hyjal at 78-79, as soon as i wasn't dying on every pull. around 83, depending on your gear/class/spec, you can move to uldum.