Interestingly, two of the patents that Oracle is suing Google over were filed by now Google employees:

I don’t mean to single out these two individuals, this is business as usual. Tech companies are pretty good at providing financial incentives to get their employees to file patents, and as long as these patents pass the simple “prior art” Litmus test, the company will be happy to file them and add them to their portfolio. I have filed my share of patents at the companies I worked on, including Sun (that was more than ten years ago).