Wouldn’t post that photo of you drinking on a beach in Hawaii on your LinkedIn profile? Then you should probably think twice before posting in on Facebook.

According to a recent study by MyWebCareer, an online service that helps professionals manage their Internet presence, 23 percent of LinkedIn contacts are also Facebook friends.

In addition, 63 percent of the Facebook profiles analyzed in the study had at least one employer listed, further showing the lines are more than blurred between professional and personal networking. The survey had a large sample size: 5,000 MyWebCareer users were profiled and their online presences analyzed.

Company Co-founder Greg Coyle offered this up as an explanation for the crossover in a press release:

We often form strong relationships with people we work with and transition them from LinkedIn connections to Facebook friends… Although many people may think that they keep their online professional and personal lives separate, the reality is that there’s a lot of crossover between the two.

The study found that LinkedIn is still primarily used to find company connections. Only five percent of companies connected through first degree connections on LinkedIn also connected through Facebook friends.

None of this comes as much of a surprise. I had a boss listed as a Facebook friend since my first internship. Does this force me to censor a lot of what I share on Facebook? Sure, but with almost 600 million users on the social networking site, shouldn’t I be careful what I post anyway? Instsead of censoring content, you can create friend lists for professional contacts and then limit what those people see — using the privacy settings on the site.

Do you use LinkedIn? Is there much crossover between your list of friends on the two sites?