It's going to be a tough year to stay current with influencers.

Under normal circumstances, Influencer50 research puts the attrition among a company's top 50 influencers at about 20 percent per year. That means that in a 12-month period, 10 of the 50 will have changed jobs.

It doesn't look as though 2009 will offer normal circumstances. I would expect that rate to climb. Large and mid-sized companies are reducing headcount, and consolidating through mergers and acquisitions. Small businesses and independent contractors may be forced to bridge lean sales by hooking up with larger companies.

It's a good idea to keep a closer eye on the top 50 influencers in each of your markets