A large number of printers now permit printing over the Internet, using an HTTP-based protocol called IPP. A smaller subset permit HTTPS for encryption. Reportedly, Windows Server 2008 does not support secure IPP, although this is not confirmed yet. Here is some info:
http://en.wikipedia.org/wiki/Internet_Printing_Protocol
http://serverfault.com/questions/45334/ipp-over-ssl-tls-in-windows-vista-can-it-be-done