If the world is going to keep up with this ridiculous process of patenting software then companies that sue other companies (sigh. . .all software companies) had better do some research to find out who supposedly has the first patent. Theoretically, you shouldn't be able to sue Google for a location based advertising patent if Apple was suing Google, because Apple claims it first. But of course it probably isn't that simple, there are probably dozens of companies around the world that can make the claim of having a such a patent.
Continuing on this hypothetical rant, what if a company in the US actually has the first patent but never sued anyone because they were too small to feel they could win? Yet when they sell their patent to a legal firm, like Apple sold patents to Digitude who could then sue companies the shell company has the very real potential to win.
Does this invalidate the other lawsuits from the other companies who filed over the same patent? Does this happen? I honestly don't know.