The major purpose of the patent as it is exploited today in the tech world has long surpassed its original purpose. Patents are like weapons-of-mutually-assured-destruction. You engage your patents, I'll engage mine. And so, we cross-license and get on with our merry lives to the detriment of our mutual competitors. This suits large businesses very well.

In the 'real' (as in physical) world there are still some good patents issued. But for computer related stuff (and that's what the bulk of Yahoo!'s patents will be about it has been quite a while since I saw a patent that made me think 'good that someone spent the years required in order to come up with this and that their rights are protected with a patent'.

I'd suggest a retro-active limitation of patents that do not involve anything physical of 3 years. That should be enough of a head-start and will immediately take care of all these ticking time bombs of patent portfolios in the hands of aging and ailing Leviathans.