Also, why is Ruby seeing such a steep decline (-51%)? Does that correspond to the state of the Ruby contracting market? On the other hand, I wouldn't have expected to see such an increase in the popularity of Actionscript. Any theories on what's driving that?
Enterprise flex development would be driving ActionScript. I agree with what jdg said about Ruby books.
Is Flex really such a big deal? I was under the impression that it hadn't really taken off?
I would say that it is taking off. Now that BlazeDS is open source, there is less of a barrier to adoption.