I stumbled across this on the web today. It appears that Markus Frind (one of Adsense's big hitters) has put plentyoffish.com up for sale for $5 million. http://plentyoffish.wordpress.com/ What I also find interesting is that further down that same page he's written:
If you're referring to POF, I don't think any has bought it yet. That article is only a few days old, 27th September 2007.