Update: Link fixed, thanks Rob.
Guy Kawasaki has up an article by Penelope Trunk on 9 "myths of the workplace". I disagree just a bit with #2 (job hopping will hurt you) and #6 (you need a good resume). Yes, if you're saying that "you absolutely must not jobhop" and "you must have an awesome resume" otherwise you will never get any jobs, ever, then yes, of course that's stupid.
But realistically, the resume and the employment history do matter. I used to interview at a place that was pretty hard to get into, the sort of place where you ran a gauntlet that required writing (and being quizzed on) source code, all the way up to getting the blessing of the company president. We turned away way, way more resumes than we accepted. Very rarely did we get somebody in by way of personal connection. Typically this was because our technical requirements were so specific that either nobody knew someone that fit them, or else they were afraid to send their friends in who were not a perfect match for fear of being blamed for wasting everybody's time. I always wondered about the coincidence that the last person I ever interviewed for the place turned out to be not even close (I was the first interview and did not ask the necessary weedout questions, apparently). I was taken out of the interviewing loop immediately after that.
Penelope's right, I wouldn't be too worried about which verb to use (did I lead the project, or did I spearhead it??). But I guarantee that at some places you are going to get thoroughly quizzed on what you say you did. You say you've got skills in Smalltalk? Great, tell me what you did. Don't lie to get yourself in the door. Since I interview and hire technical people, one of the rules of thumb I've always used is, "If you list it as a technical skill, then you'd better show me in the work history where you used it."
As for the job hopping, that's a hard one. You don't want to tell people they have to stay in a horrible job for a year just so it doesn't look bad on the resume. What looks bad is a pattern of that. Fine, you left one job because it wasn't a right match, or because the boss hated you, or you got a better offer. But if you did that 5 times in 3 years? I'm going to have to wonder whether you'll do that to me, too. If you're having that much difficulty finding a job you like, then how am I supposed to know if the job I'm offering you is going to be any different?
Don't be afraid of the great big working world. There's room for everybody, and almost nothing that you can do will be such a black mark that you'll never work again. But by all means treat your career like one big entity, not just a series of jobs. What you do with your life says something about you. You're not getting a clean slate every time you end one job and start a new one. You need to be able to explain why you made the leap that you did. There's a certain level of accountability there. Your new job expects you to be accountable for your actions, and that resume and interview are really the only things they've got to base their decision on.