Barely 7 months after I first came up with the idea of using Google Alerts to find out if your website has been hacked Google has officially decided it’s a good strategy to use.
Check if abused URLs are showing up in Google. Try a site: search on your site to see if anything unfamiliar shows up in Google’s results for your site. You can add words to the query that are unlikely to appear in your content, such as commercial terms or adult language. If the query [site:example.com viagra] isn’t supposed to return any pages on your site and it does, that could be a problem. You can even automate these searches with Google Alerts.
Why this can’t be pushed as a service via Webmaster Central isn’t clear but at least things are moving forward.