stable is *old*. It's missing pretty much every bug introduced anywhere in about the last two years, a luxury that any more recent distribution doesn't have.
Like:- http://www.theregister.co.uk/content/55/25608.html ;-)
(Of course, it's also missing most features introduced in anything during the last two years.)
Which is why I run testing. stable would be fine for servers, but I like using my home computer to the best of it's abilities.
If you're not running stable - well, security.d.o doesn't have updates for testing and unstable.
Well, surely *someone's* scrutinising the security of the new packages? And Woody was set to be frozen in May...