As we previously reported, Oracle America has filed suit against Google for (primarily) patent infringement. If you're not familiar with the case, I'll quickly summarize.
Oracle claims Google is in violation of seven U.S. patents previously filed by Sun Microsystems as part of the Java platform. Oracle now owns Sun. The alleged infringer, more specifically, is Android. If you want a more detailed explanation, read the next paragraph. If not, look at the pretty picture and continue.