I don't think there's a specific format necessary - this isn't for a resume book, and applicants come from all over the place, so I assume they see an enormous variety of formats.
However, a few points I've heard from various adcom folks:
1. Chronological, not functional. Show them your career projection. For b-school, it's really much more important that you're an achiever who rises in the ranks than a person with a specific skill.
2. Put down all promotions, even if you've had a ton of them at your job. Again, show the progress.
3. Understand that the person reading it may not know what the heck it is you do - don't get jargon-y.
4. Action words - this is old resume news, but still good
5. Be quantitative: "Saved the company money" is less exciting than "instituted streamlined operations resulting in savings of 15%" or whatever
6. Include months and years for jobs.
That's what I can think of as I mosey off to bed. Anyone else have ideas? It might be worthwhile to put together a semi-comprehensive list.