Looks like RubyForge just went up over the 20K user accounts mark; now it's at 20,188. Some of these accounts are inactive, of course, but, still. Here's a chart of RubyForge growth since we stood it up a couple of years ago - click on the chart to see the full-size image:
The growth seems to have levelled out in the last nine months or so, but it's still pretty impressive - around 35 new users each day. And of course that doesn't include the tons of people who do "gem install rails" without having a Rubyforge account. Good times!