Java top 5 technologies to learn during 2008

I receive regularly emails from several technology sites. This time one carried an interesting link to a blog entry describing the top 5 technologies to learn in 2008. Some interesting ones, a side the usual web 2.0 ones, are OSGI (at #5) and Cloud computing (at #1). I have been exposed recently to cloud computing and grid computing doing scalability work for SpringRing (now Aloha). But, I must admit, I was not aware of OSGI.
Oh dear, something else on the stack.