You know, now that we're talking about it I'm wondering if someone hasn't already come up with a better bot and has just been silently using it to win money online.

I'm sure the sites have been crawling with bots as long as they've been around, some better than others. As long as it doesn't drive away too many customers I doubt the sites care. They still take a rake on bot games. However better AI could change that as the "dumb money" slowly dries up.