After a few queries on DICE, I discovered that "Rails" is now officially a synonym for "Ruby": there are nearly 50% more hits with the two words than with ruby alone. So I've adjusted the DLJB scraper accordingly, and Ruby's numbers are much more respectable.
I also did some searches on a few other languages (Erlang, Haskell, Groovy, Lua, and Lisp) to see how they're faring. Pretty well, it turns out, esp. Groovy (lookout, Ruby and Python, objects in the mirror may be closer than they appear...). So I've added a new "Others" datapoint to the chart.
Alas, one troubling note: Perl's general numbers have eroded slightly (about 6-7%), though the "titles only" number seems to be holding up well. PHP is still growing at a steady clip. Python seems to have plateaued. Maybe Google AppEngine will breath a bit more life into it. (I know I'm going to have to learn to stomach Guido's indentation, as my new overlords have adopted it for their test environment. So my OSCON will be Python heavy this year.)
On a positive note, however, the overall numbers seem to be holding up quite well, despite the current economic woes here in the US.