And Martin is quoted:
"First of all, what they bought is crap...Motorola sold off its good assets. Back in the day they sold off their MPEG patents to GE in a securitization deal, after that they took a bunch of the Freescale patents and sold those."
SeekingAlpha paints a broader picture, suggesting Google bought Motorola for tax losses, and the patents were merely window dressing:
You are allowed to utilize the tax losses of a company which you purchase: but you're not allowed to go and buy a company just to utilize the tax losses. The IRS says so. So, if we were to imbue Google with Machiavellian cunning (GOOG's reputed to have pretty bright guys, after all), then before purchasing such a large cash value of tax losses GOOG would establish that GOOG was absolutely in the market for something else that comes with the deal. Thus, bid on the Nortel patents to establish that it's that patent stack which is being sought.
On the conventional side of the coin:
PATENTS NOW DRIVING FORCE IN TECH ACQUISITIONS