Still use the same Bulldog billy can set I've had for 40 years (amongst other pans), stoves change all the time depending upon which one or two I pick for a trip. Stove technology has not changed a great deal in decades, things like the Pocket Rocket are good, but don't forget cookers like the Epigas Micron stove made about 30 years ago, just as small, just as good.
Sleeping bags have got worse for me in some respects, when a keen hillwalker many moons ago I always spent top dollar on down gear which I haven't done in recent years but this may change and I'll treat myself to something really nice for next winter (I need more warmth as I get older)
Tents; I have the Hex which is great, but I'm back using Force Ten's now, I have a Mk3 and now two Mk5's and I must say I have fallen in love with this range all over again, they are a blast from the past and bring back many happy memories for me (I'm looking for a Mk4), and I need a family sized tent before summer 2010 for the wife and grandson.
Clothing has changed, in the past when young I wore Levi's or climbing breeches and used PU Nylon rainproof trousers, these days I tend to use lightweights or M65's and gortex trousers. With jackets I started off with WW2 army para tops (wish I had them now), moved on to Ventile, then fleece and PU Nylon anoraks, these days its a mix of fleece, down, gortex. I've always liked wool jumpers of any type or make so that has remained the same.
I enjoy a better range of food now than when a youngster, back then corn beef and smash were a staple along with dried meals (yes, you could get dried meals 40 years ago), these days as I only 'base camp' I can cook whatever takes my fancy.
One massive improvement in kit for me over a 40 year period is the humble torch. LED torches are perhaps one of the best things to happen in camping ever, fantasic technology, no dead light after an hour, no need to carry masses of spare batteries either, wonderful stuff.