What exchange rates does the client use to compute the fiat value of the wallet balance? It seems to overvalue Bitcoins quite a bit.... not quite as much as if you were using the Mt. Gox price, but close...
It's using
bitcoin charts, which averages all exchanges (and 24h of time) weighted by trade volume. So yes, Mt. Gox is in there to some amount.
Perhaps it could use the new Bitcoin Price Index (at least as an option)?
What's that?
Google does not know about it.