I think the bids Google made were good geek fun. Round numbers don't imply anything. In the background Google had a max $ amount on what they would pay and the bidding eventually went over it.
Good luck to the companies who won the bidding on getting their $4.5B back. I'm sure the analysis done at Google went something along the lines of we'll just infringe, get sued and then pay the few hundred million + licensing and still pay less than $4.5B. And before you jump on Google for this, all companies make these risk/ROI decisions everyday. It's exactly what Apple did with respect to the Nokia patents.
google is not going to infringe, HTC/Motorola/Samsung/LG and other handset makers will.
the idea is to make android too expensive and get them back to WinMo/WP7. RIM and Apple and a few others having access to the patents is just icing on the cake