Prevailing economic conditions?
I dunno, seems a bit suspect to me. My suspicion is that Nokia's lawyers and accountants have looked at what's going to happen in the near future (their buy-out of symbian is not just strategic - they now have no per-handset royalties to pay to symbian) and both parties have agreed to give a little, but Nokia has had to give more.
They've decided that it's better to feel a little pain now than have it magnified when Qualcomm won later and hit them for far larger payments. Besides, some of the more improtant (and lucrative) patents (W-CDMA in particular I'd guess) could well be more attributable to Qualcomm.
Just another American Commercial Imperialism vs European approach battle? Stalemate? Let's face it, the Americans probably wouldn't call off the hounds unless it felt like they won, that's what they're like. Any word from Qualcomm about how they feel?