I would trim any plant material that has actually died. If it has green or red, it has life.

Same advice from me. I trimmed all the dead brown pitchers today on mine. On some I only trimmed the top, dead half and left the living alone.

My nursery:
{{gwi:564082}}

A lot of my sarrs appear to be going dormant now, so I've cut most of the dead pitchers almost to the soil level. During the growing season, I'll cut off any pitcher that's completely brown and dried. For the ones that are half-dead, I don't lop them if it looks like the green part is still digesting bugs. And I don't remove the dry tops if it looks like the plant can still be catching prey.

I agree with ltecato in that cutting off the top of a partially dead pitcher would allow rain to enter the pitcher and dilute the ensigns. If bugs are still being digested in that pitcher this will stop the process until some of the water is used by the plant or evaporates. I would leave them alone until the individual pitcher/trap is completely dead, all the way to the soil level.

Before I put my sarrs in the fridge for the winter (in October sometime) I cut all the pitchers off, except on Purps. I only cut off the dead pitchers on those.

These are some great responses (and photo!), thanks for the input!

OK, so here's another question: what if the pitcher isn't dead, but deformed (from aphids, probably) in such a way that it will never catch & digest insects? Cut those off too, or keep'm around for the chlorophyll?

I would keep them. The plants need all the energy they can store at this time of the year. They will be dormant soon and need that energy to start fresh in spring.

I would treat the aphids to either drowning or Neem Oil or Schultz' Garden Safe.

Oh, the aphids were dealt with :) But if they do enough damage to young buds, the plant will grow distorted.

I'm curious then: how many of you cut off pitchers before hibernation? How many pitchers do you cut off?

I've only had mine for two years now (one winter). Last year I didn't cut off any pitchers, and kept them mulched (enough to go 2 inches over the pot). They didn't seem to spring back as strong this summer and I'm not sure how much of that was their winter arrangement or if I took them out too early.

I'm in Pittsburgh, PA (FYI)

Like Tommy, I cut off all pitchers after going dormant(except purpurea). It's not necessary with S. purpurea because they are more compact but I do cut the dead ones off. I also dust them with sulfur to keep mold at bay.