Just came across a feature at the top of the SERPs which I haven't seen before and I haven't seen mentioned here (however I'm sure people can point me to many posts about it on WebmasterWorld!).
When you search, for example, for 'marketing careers', 2 form fields appear at the top of the main SERP headed "Refine your search for marketing careers". They allow you to enter your zip code/post code and to select the job function you're looking for.....eg banking, engineering etc.
On submit, Google then takes you to another SERP listing showing Google Base job listings and a map showing the location of those jobs in your locality.....very nice.