I saw recently on the Google blog that the Googlebot will start submitting web forms.

Specifically, when we encounter a <FORM> element on a high-quality site, we might choose to do a small number of queries using the form.

I saw this curious line in my log files today:

212.36.25.102 - - [06/Dec/2006:17:00:50 +0000] "POST /suggest.cfm HTTP/1.1" 200 232 "-" "Googlebot/2.1 (+http://www.googlebot.com/bot.html)"

That's GoogleBot doing a POST operation to suggest.