I'd like to know if its possible to share a printer connected to a Windows machine to print a document from a OpenBSD machine.
I know that Windows XP Pro, and Win2003 Server, ship with a BSD print daemon that can share the printer, (you have to purchase it for other versions of NT). Windows usually works better as a client to a BSD lpd box, though. However, you can also try samba from ports. I've successfully printed using both methods. You'll need to do some work reading documentation on ghostscript, samba, printcap, and in Windows on UNIX print services. So the basic answer to your qeustion, is yes, it is possible, but may require some work configuring.
