Thank you boost developers for your great work. I've already started using some smart_ptr's, regex, and the any type. I started to look at shared_ptr for my needs (working in a realtime embedded systems environment). I started wondering how it protects its reference count but was surprised to not see anything about this in the documentation. Examining the code I see it uses a platform specific mutex type mechanism if it is available. Otherwise the reference count is not thread safe. I was also alarmed to see that the #error "your reference count is not thread safe" was commented out! Just a suggestion: mention in the documentation whats going on here. The operating system I am using (VxWorks) is not supported by shared_count right now, and had I not been curious I would have not noticed this. Also, even if it was, it can be very expensive for a realtime embedded system (e.g. running on a very slow processor) to take a mutex, especially if done at a very high rate, which is a concern of mine in a few places in my code. BTW, can I submit a VxWorks version of shared_count? Does boost have an interest in expanding beyond Win32/Posix/Linux? Again, thanks for the great software, Brian Neal