It also depends on the exchange you use as well. MtGox may say one thing, but the exchange that you use may say another. My advice, use the rate from the exchange you trust. I use Coinbase.com. The highest that i have seen is MtGox, however, people don't like them because of all the problems they have been having.
I've been using MtGox to watch the value etc, but I've never traded/purchased anything on there. Also they require government issued paper before you are able to do anything useful.. Is that normal..? I mean, I haven't used coinbase before and I'm wondering if they also require something like that in order to sell/buy bitcoins because I'm soon looking to sell some bitcoins.