I'm sure most of this was due to the fact that I spent most of the month looking for work or waiting for projects to get started. I tried to keep busy with personal projects and whatnot, but when I finally did start on a Rails job at the beginning of this month, it was a bit distressing how rusty I felt. Part of this was also due to picking up both RSpec and the new Restful style, which was a bit disorienting. (Though Geoffrey's excellent PeepCode screencast helped a lot with that; give it a spin if you're having trouble.)
I'm thinking I should take this as a bit of a warning to practice Pragmatic-Programmer-style continual learning. It was a pretty jarring experience, but it helped remind me that staying sharp and active is a really important part of maintaining competence. Falling into complacency is easy to do, especially when you really feel on top of your game, but it gets you nowhere.
On an entirely unrelated note, when I was first getting into Ruby (around RubyConf '05), I joked about how "Ruby is becoming Lisp" because of some superficial changes regarding how parameters were specified. Well it turns out some of the stuff they're doing with Rubinius could make that a reality; you should be able to feed the Rubinius straight S-expressions, and from there it's a short leap to providing a defmacro facility.
Which is cool.