ITT YOU MAKE THE CLAIM RUBY CAN DO EVERYTHING

BECAUSE YOU CAN ALWAYS CALL C CODE TO DO IT RIGHT. AM I RITE?

I AM

it's not like caching it will do too much since there will probably be an update in the next minute or two.

I disagree. Considering the type of traffic that digg.com must be getting, caching would hugely benefit it. The overhead of a dynamic page is so high that all it takes is two hits instead of one to make caching a win. And you can bet digg serves more than two pages between updates.

Now, I've never used Ruby to serve webpages, but if you use FastCGI and a dose of static HTML, I'd be very surprised if you couldn't make a heavily-loaded site, unless it's something like Amazon's shopping carts.  I'll also point out that Ruby and PHP are comparable for speed; if you want a popular fast scripting language, you should be looking at Python or Perl.