That was a good article! I would not worry about how fast WebSockets catch on with the general public: even if in 6 months only a small percentage of web users have a browser that supports WS by default, that is still a lot of potential users. Really, a great looking technology.
It's also possible to fully "backport" WebSockets through a flashembed that acts as an intermediate layer. Flash has about 98% penetration so this should make the technology usable right now. Especially with an eye to a future where the flashembed will be loaded less and less when browsers start to implement it natively.
Very clear write up on WebSockets in general and Ruby/EventMachine in particular. Loved the examples!