Indeed.com has an excellent tool to examining trends in the job market. Indeed is a search engine for jobs. It visits thousands of sites, job boards, company sites and bulletin board sites, and captures information about posted jobs. It then allows a job seeker to search all the results.
If you haven't started using Indeed, you should add it to the selection of sites you search. It is very comprehensive and can be almost overwhelming.
One of the features Indeed offers is a trends search. You can search a keyword to see the trend for job postings mentioning that term.
Although the economy is slowing and jobs are becoming more scarce, this isn't happening evenly across all jobs. I took a look at the trends for different educational levels, and the results are interesting. Jobs mentioning a high school requirement have increased significantly over the last fours and show a slight drop in the last few months. Jobs mentioning a Bachelor's degree show a similar trend. MBA's are in a significant downtrend and do not show any job growth over the last four years. PhD's are holding strong and have been increasing over the last two years.