Mine has the PCV on the passenger side. I took it out and shook it and it rattled the other day so it must be PCV. I don't think it allows air in it ventilate your engine so you don't blow seals. (positive crankcase ventilation) I was wondering if there was two of them and what the hole in my other valve cover is for.
The pcv works like a cycle though, it sucks air out on one side and puts it back into the intake, the air has to be replaced somewhere considering the crankcase is sealed, plus if it lets air out on that side you'd have unfiltered crackcase fumes going into the intake. Thats why I assume its an intake for air.