Is there a somewhat standardized USD/BTC exchange rate, that is indexed over *all* of the exchange sites rather than just Mt.Gox?

As more merchants adopt bitcoin payments, it will be helpful to have a single reliable exchange rate that can be grabbed from a known location.

The 1-day weighted average for Mt.Gox is available from the Trade History tab at bitcoincharts:
 http://bitcoincharts.com/markets/mtgoxUSD_trades.html

That is a decent estimate, but we really need a weighted average over most or all exchanges (we need to decentralize this critical function).  The smaller volume sites won't have much impact on the weighted average right now, but implementing this now will allow a smooth transition as sites like TradeHill and Camp BX gain market share.

Wait, is the value reported on the front page of bitcoincharts.com and in
 http://bitcoincharts.com/t/weighted_prices.json
the indexed rate over all exchanges?  If so, that guy is totally awesome, and i'm totally hitting him with a big tip.