If everyone out there knows the technology in question and you don’t, that seems like it would be a problem for your marketability. ;)

I agree it’s good to learn the next big thing, but if all of my contemporaries know their way around Hibernate and I don’t, I’m at a disadvantage.

In Chad Fowler’s book, “My Job went to India and All I got was this Book”, he argues that spending time learning what is hot today is not an effective way to be marketable, because there are already so many folks out there who know the technology in question. Essentially, it is now commodity. The real value in the graphs you have assembled is looking at trends and using a little guesswork (and getting a little lucky), you can learn the technologies that will dominate in the near future.

As Demian pointed out, any good developer can pick up most of the currently popular stuff quickly (lots of books and websites), but for interviews, it is probably a good idea to be able to discuss at least the high level aspects of the most popular of them.

It’d be interesting to know more about Struts2. Interesting to see that JSF is so low. I’ve used it briefly, had a 1 week class and as far as I’m concerned it’s entirely crap. Be weary of guys in suits selling expensive tooling.