Scalability of Rails Applications: Does Rails Scale?

I saw this article today. 

The exec summary:  Sure Ruby on Rails scales and so do most frameworks if you use them correctly.  But, scaling sites is hard work and so many people forget that it has a HUGE amount to do with the actual code and how that code uses the database (or not).

Over the weekend I also ran across this article of a Rails based facebook application that is pretty much exploding at the seams.