[rabbitfang]

"Did IBM fork Java when Oracle bought Sun? If so why isn't Oracle going after IBM"

IBM has had their own JDK implementation for more than 15 years. April 6th 1997 is about as close a date as I can find: http://www.os2ezine.com/v2n7/javarev.htm (that's version 1.0.2, so it's probably even earlier).

IBM have a license and produced a fully compatible implementation. Before Oracle bought BEA (who bought JRockit) there was also another independent commercial JDK implementation in addition to the IBM and Sun/Oracle ones.