In particular, the VirtEx exchange in Canada often trades at around 10% higher than mtGox.
Typical bid/ask spreads at mtGox are around 1.2% to 1.6% of the BTC price, with most bidding trading around the even dollar and $0.50 marks. It’s common to see $5+ spreads, but those generally close up pretty quickly.
Spreads on the VirtEx are typically wider than those at mtGox with $5 spreads being common for much longer periods.
The larger spreads seem to indicate some hesitation or uncertainty, but the consistently higher trading prices at VirtEx indicate that Canadians are quite bullish on bitcoin and willing to pay a bit more simply to get it easier and faster at another exchange. Why wait days or weeks to get on an exchange when you can get into the VirtEx market almost immediately? The price is rising so fast that even if BTC is trading higher, you’ll come out far ahead.