SPSite.BypassImpersonationStateCheck - a mystery showing up in Sharepoint error logs

In the process of tracking down an elusive Sharepoint custom workflow problem, I cranked up the verbosity level on our sandbox MOSS server and noticed the following error message start popping up:

SPSite should not be used with mixed impersonation state. If you do want to cache an SPSite created within RunWithElevatedPrivileges, call SPSite.BypassImpersonationStateCheck

While this is most likely unrelated to our problem, I was curious about this SPSite.BypassImpersonationStateCheck m开发者_开发技巧ethod that doesn't seem to actually exist. When we include this call in our code it won't compile. MSDN doesn't have any information. A quick Google search doesn't turn up any concrete answers. What is SPSite.BypassImpersonationStateCheck?