How many of you are using 2e, and how many 3e?

House rules mostly, based partly on 3E. I try to keep the rules to a minimum.

Kind of a hybred but mostly 3/3.5 with adjustments made on the fly by myself (The DM). I never really used the stats as heavily per say in the books as most would. I use it as a basis and use the story/information outside of stats as the real information so to speak. Makes it much easier to simply use without a ton of messy conversations.

3rd, but its what I came into as well

3.5, with house rules.
Some D20 Modern and Future elements (It's planescape, why not?) and lots of other things.

3,5 with a 3,0 npc generator. I'm not a rules facist and i let the players make just about anything (wanna be a green ooze wererat? No problem ) because i like it mostly for roleplaying and some simple combat to let them blow of some steam after having to talk to my weirdo NPC-s

I also try to use the 3ed rules for planar magic/aligment restrictions, but add a few flavory things from 2e (illusions don't work on arcadia, low air pressure in sigil, using int as dex and wis as str on astral...) just to surprise them with some weird conditions they didn't bother asking NPC-s about

I use the HERO system. Or, rather, I will. A friend has my book right now.

I play gurp occasionally and i love the detailed combat, hit locations, fatigue loss, block, parry and everything else. But planescape is, to me, the perfect setting for dnd because the world is based on aligments and aligments are the fundamentals of dnd roleplaying. Gurps has no good, evil, law or chaos, it has mental disadvantages instead, so i don't see it as a very suitable system for planescape

Then again, planescape in gurps... Sounds almost crazy enough to work. What would be the point cost for chaotic-neutral-good?

Oh, describing alignments in GURPS is easy....ahm, well, no, it's not, since there is no such thing as 'Alignment' in GURPS. But I don't think that you need aligmnent for planescape. Planescape is IMHO primarily based on beliefs. And you can formulate beliefs easily in GURPS as disadvantages or advantages. Take a lawful good aasimar paladin for instance. You don't need to say the two words "lawful" and "good" to describe him, instead you could give him (GURPSlike) a code of honor, a sense of duty, an inability to harm innocents, a higher purpose - all of which are given point values in GURPS.

Chaotic-neutral-good. Characters who don't depend on their alignment, but on their individuality to be played well, they can be built without paying much attention to alignment at all.

What I really like about having alignment put out of the picture is that it's much harder to pin labels on people. Baatezu, Harmonium, etc will be judged only by their deeds and the beliefs they spread, not by the tag Lawful or Evil.

I try in my campaigns to let the rules fade into the background and to let the unfolding story speak for itself. I think that's possible with every available set of rules.

I looked at the 3E Manual of the Planes and such, and thought it was pretty much universally rubbish. Like all 3E products, I don't see a labor of love and creativity and story, but simple 'I AM TEH UBER' mentality - banal and boring.

I recently bought nearly the entire library of 2E Planescape books off eBay, and they're just as good as I remembered. They're works of art and story, and I love them. And while I may never play or DM Planescape again, I just love having the material. It's sublime.

As far as rules go, I'm attempting to adapt the WFRP system for use with Planescape. Failing that, I'll just use old 2E rules.

I find myself in a similar situation, Xan.
Though I play D&D with a group of people (3.0/3.5), I never actally got them interested in the Planes. Then again, the actual roleplay-factor in our campaigns is kinda low, and most scenarios are limited to combat.
Pity.

I've been running a PS campaign in 3.5 (My players are all in their low to mid-twenties), and it's been working out fine for me. I've found that its not the breadth of Planescape to be tied down with rules lawyering and concerning issues of game mechanics. Most of my players are playing things they normally wouldn't touch in a "standard" setting, and they're having a blast. The material is what's important for a PS campaign, not the version of mechanics you run.