What is the highest level you can reach in skyrim? I've heard it was lvl 81 and then i heard it was lvl 255. Which is it if that???
That depends on whether or not you've updated your patch.
With patch 1.9 you can effectively level indefinately(I beleive) by resetting your skills and re-leveling them.
Before that, it's 81.
Dmoontear is absolutely right if you game is fully updated there is now no known level cap. There is a thread here where people are saying what level they've gotten up to.