You could try a new tool I spotted via SEOmoz that tries to report if you've been banned. It sees if you have pages coming up via the site: command in Google. If not, that's sometimes a sign you've been banned. It also uses a second method to check if you've been banned, though exactly what this is isn't documented. There's a thread about the tool here, but really doesn't cover the second method.

http://123promotion.co.uk/tools/googlebanned.php