We were wrong about that. Recently, we started observing Googlebot making POST requests to thumbtack.com. As far as we can tell, such requests have not been openly observed before. These Apache access log excerpts show a few examples:
188.8.131.52 - - [04/Sep/2011:04:53:52 +0000] "POST /act/site/clienterror HTTP/1.1" 200 36 "http://www.thumbtack.com/ma/malden/dog-walking/dog-walking-and-pet-care-services" "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)"
Tiens v’la aut’ chose ! Ils nous crawlerons jusqu’à la dernière goutte !