His argument is that slow languages are acceptable now because databases are slow due to slow hard drives. But this seems not right to me. Most databases eat as much RAM as they can get their hands on, and in any reasonable sized setup, the frontend and database will be on different servers so you still have to factor in internet work transit time. What this boils down to is that harddrive speed increases won't make as much of a difference as he is counting on because

a) They aren't necessarily the biggest bottleneck now

b) Even if they were a bottleneck, we still often have network transit time to account for, making DB access still relatively dog slow.

This doesn't even take into account the entirely different set of arguments that other languages like php and python are an order of magnitude faster than ruby 1.8 (and ruby 1.9 is faster too) and that Java is considered by many a horrible language, and no speed increase in the world would make them willingly use it.