So where are we at at? KDEPrint could be broken into 3 parts, the underlying library for communicating with the supported Print Systems (CUPS, LPR, etc), the Application Support (Print Dialog, Print Engine, etc), and the Print System Management (add printer, job viewer, etc).
Application support is where we have switched to dependence on Qt for the Print Dialog, Print Engine, and submitting jobs to the underlying Print Systems. Qt4.4 has seen the addition of a reworked QPrintDialog for UNIX that bears an uncanny resemblance to the KDE3 one, official support for extending the dialog with our own options, and new features in the Print engine such as improved support for duplex and margins. A number of features haven’t made it into Qt 4.4, some of which we will have to work towards being included in Qt4.5, but some of which we can add to QPrintDialog when printing through CUPS. Below are screenshots of the support I’ve added for various Page and Job options. There's still a bit of polishing work to do, and I'd welcome some new icons for n-up printing similar in size and style to the Colour Mode icons on the Options tab.
Print System Management for UNIX is still a problem that needs solving. I had planned to work on KDEPrint for inclusion in 4.1, but haven't had the time, so sadly there will be no resurrection of the famous KPrinter utility this release. Instead, for 4.1 Jonathan Riddell has added printer-applet into kdeutils, a port of Red Hat's system-config-printer tool, to cover some of the missing functionality, itself a milestone of sorts in being the first Python app to be included in the main KDE modules.
Longer term, the future of KDEPrint is uncertain, especially with many distributions continuing to implement their own Printer Management tools. On the application side, there's an interesting collaboration between OpenPrinting and OpenUsability for a unified printing dialog with a Google SoC 2008 student attempting a first implementation.