I do a ton of patent and IP litigation/infringement work. I was doing some research on recommendation engine/e-commerce patents last year and came across a good number of patents from IBM with good priority dates, so it was no surprise that IBM is suing Amazon.com over patent infringement, alleging the online company knowingly built its business on five technologies IBM owns. Apparently, it is a more of a tactical ploy by IBM to force some sales at Amazon which has been tied to HP.