Edit: and indeed it would be nice to know if a company like Google etc uses OpenJDK or the Oracle one.
If you fork, be prepared for a patent-infringement lawsuit as soon as you earn some money with it.
I'm pretty sure most companies have realized that staying the hell away from Oracle isn't a stupid move.
The amount of paid "consultants" that oracle pushes thru to make their sale, plus their tactic of charging what you can afford to pay, as well as the "can't get fired for buying IBM" mentality of large IT organizations means that oracle has a distinct advantage over any small competitor.
Not that oracle's tech isn't good, but there are comparable alternatives, but they are only comparable in the technical aspect, not in the (strongarm) sales aspect.
I worked with Java since 0.1 in the enterprise world for over 10 years and with Clojure & Scala I would continue with it, but I don't trust Oracle to do the right thing in releasing source at the same pace or at all for some critical perf/scaling features and I tend to think thats wrong.
How does OpenJDK handle serverside compared to the Oracle binaries these days?