Amazing. I've always known about this, but I've never heard of anyone actually being called on it before unless they were releasing code that was directly relevant to their job. Rational companies know that trying to enforce this will just piss off their employees.
Assuming you have a good rep at this company, are they really willing to risk losing you to stop you from doing this? It sounds like one of those lawyer-driven things that the people who actually appreciate your work there would not stand for if they knew about it.
Anyway, I think you can find much more open source friendly jobs right here in NY. I interviewed at a couple of places that did lots of perl and were well aware of the relationship their employees have with the rest of the perl community.