Comment 12 for bug 632314

I noticed that this very topic (the default file descriptor limit) is currently being discussed on the ubuntu-dev mailing list.

In particular, there was a little discussion of the fact that /etc/security/limits.conf does not apply to services:
  https://lists.ubuntu.com/archives/ubuntu-devel/2010-September/031493.html

The thread also covers various situation where otther applications are hitting the limit; if you (Alex) are lucky perhaps something there will give you an idea why you are doing so but other sites don't seem to be....

Nathan