I just found URL's with 5 variables in the string appearing in the URL in Google's results. Could this be how their pages indexed went up so drastically recently?
The interesing thing is that it was cached back in May:
Possibly these have been in the system for a while and recent changes allowed Google to start including these pages in the results?
I haven't been following things as closely as I should, so if others have already noted this, my apologies. But I found it interesting to suddenly see these URL's in the SERPS.