Brett_Tabke - 11:49 am on Apr 10, 2001 (gmt 0)

There are several ways a search engine can detect programmed over hand submission.
1) user agent. Many autosubmitters clearly identify themselves.
2) cookies (tastes like chicken). Many are tracking submissions with cookies.
3) headers. Browsers and bots can put out different headers.
4) speed of submissions. some auto bots rapid fire off the submissions.
5) refering string. Some se's want to see a referring url from their server.

That about covers it...