As I look over the recent updates posted by my various friends on Facebook, I think I can safely say that most of them work for companies that don’t spend a lot of time keeping their employees off social networking sites.

Last summer, I mentioned a survey by the Chicago-based job consulting firm Challenger, Gray & Christmas that found only one in four companies were blocking access to social networking sites.

The survey found that most companies (59 percent) don’t actually have any sort of formal policy targeting sites like Facebook and MySpace. In fact, nearly half of them said they were only concerned with whether or not their employees got their work done.

This is why I was a little surprised at the results of another, much more local, survey that popped into my email box. The survey was done by AAIM Management Association, a group of 900 St. Louis employers.

According the group’s recent survey of members, 70 percent of them said they allow access to the business networking site LinkedIn. That tracks pretty well with last year’s Challenger survey.

But when the subject turns to the more frivolously social Facebook and MySpace, things take an interesting turn. Half of the survey respondents said they don’t allow employees access to those sites. (The thought of this would make many of my own co-workers shudder.)

So I wonder. Are employers in St. Louis really that much more restrictive when it comes social networking? Or maybe it’s just that a lot changed during the six months or so that separated these two surveys. Maybe employers are just growing tired of watching employees play Scrabulous, er, I mean Lexulous.

I’d love to hear from some local companies that do or don’t block access. What are the pros and cons?