I'll continue to post information about PrintTicket here & answer questions, however I want to also point people to a few other place that may be of interest:
http://winfx.msdn.microsoft.com/ (WinFX® SDK September CTP 2005)
http://windowssdk.msdn.microsoft.com/ (Vista™ Beta 1)
XPS Team Blog:
Primarily focused on the XPS format, but includes information about how PrintTicket as it relates to XPS.
You'll find a talk about PrintTicket specifically, as well as talks about a number of other printer-driver related technologies.
http://www.microsoft.com/whdc/driver/foundation/DevNotes.mspx (look under Printing Architecture and DriverNotes)