Well, a resume with 10 jobs on it is just a badly designed resume. Who cares where you worked 20 years ago? Drop in the three positions you feel are most relevant to this application, not everything you ever worked on.
This makes a fair bit of sense, but how does it fit with employers poised to jump on any career gap (which I guess you could say is a warning sign in itself -- but seems to be common)
One thought would be to do it like academics do with "selected publications" and have a section called "selected experience" or "relevant experience".
What I've done in the past though is simply mkae the older stuff increasingly terse to the point where the really old stuff is just the dates, company and title.