wyweb - 12:19 am on Apr 11, 2011 (gmt 0)
Put some phone home stuff on your page and then keep an eye on your logs. You can often get on top of it before the SEs even know it's there.
Most scrapers are stupid. They'll leave an absolute URL in there just because they're too lazy to look for it.
And then break out the DMCA guns.
It's always worked for me.