perhaps someday.  Today, I prefer to get the information directly from the exchange.  Not to say I don't trust bitcoincharts, but I don't want to risk my own prices being affected by a bug or security breach there.  Also, I don't know enough about all of the different low-volume exchanges (and the security of them) which go into the weighted price they report

for me, bitcoincharts is a nice visual tool to see market data at a glance.  But when I need to do real money transactions, I want the up to date data directly from the exchange