[boost] [serialization] Thread safety question.

Hi. Some pages on the web (e.g. http://www.rrsd.com/boost/index.htm) and some old news posts seem to indicate that the current trunk version version to be included with Boost 1.36 makes the library 'thread safe'. What exactly does that entail? Can two separate archives be created in two separate threads? Was that not also true with the version included in the Boost 1.35 library release? Many thanks. Best regards, Jurko Gospodnetić