The FTC weighs in on patent reform (opensource.com)

I'll pull a figure totally out of the blue and say that at least 95% of all apps in the iPhone app store violates at least one patent (probably 100% and probably a lot more than one patent).

Also, it's hard to do a patent search even for a really large company with huge amounts of IPR lawyers. The main reason is that not only is the body of sw patents extremely large (mainly due to cover patents), these patents also get interpreted quite widely, and often you need to read the patents through-and-through to fully fathom its ramifications -- the summaries are rarely sufficient.