Panda punishes "thin content" pages, so it's unlikely that they are making any money off Google search results. From what I've seen, all but the most common domains don't make much money off of type-in traffic, either. (Sedo, for instance, shows traffic to the domains parked with Sedo when you run a search for a key term on their site. The traffic is nearly always negligible.)

This is probably a consequence of newer browsers redirecting queries they can't understand to search engines vs. auto-completing a domain name.

From what I can see, most of these folks are just hoping some sucker is willing to come along and pay money for the domains. Sometimes it works; most of the time it doesn't, but that doesn't stop people from doing it because they figure one "big hit" is worth all the money they spent buying domains. Sort of like buying a lottery ticket, but slightly smarter.

Most parked pages make very little from search engine traffic. Very few were listed anyways. A couple domain parking solutions were trying to get around this but adding content hurts conversion rates on ads. The better names still get type in traffic and straight ads convert better on that.

I don't think search results were ever the driving source of traffic. A lot of places experimented, none really blew it away, so I can't imagine panda had much impact on the bottom line of any major players.