I've written a little web-app to monitor Bitcoin exchanges on your smartphone. The stats automatically update every 30 seconds and can also be refreshed manually. So far it only supports MtGox and CampBX in USD:http://bitcoinwatch.mobi
If you're using it from a regular browser, it'll look much better in Chrome but it should work in Firefox, as well. I haven't tested with IE.
Let me know what other features you'd like and I might just add them. Also, if you find the site helpful, I'd appreciate a click or two on my banners to help with my domain and hosting costs. Thanks!