We said in TidBITS-146 that Hewlett-Packard had come up with a Portable DeskJet, but no corresponding Portable DeskWriter, a seemingly-obvious move given the popularity of the PowerBooks. We don't have news about a Portable DeskWriter, but it turns out that you can achieve the same functionality using the PowerPrint 2.0 collection of printer drivers from GDT Softworks.
Generally available for about $95, PowerPrint supports over 1,000 printers, and according to Steve Gully of GDT, the HP DeskJet 500 driver works fine with the Portable DeskJet. PowerPrint includes a spooler and a parallel-to-serial converter cable for hooking to printers that only have a parallel port. If you travel regularly with a PowerBook and want to use printers wherever you end up, PowerPrint would be a good addition to your travelling kit.
GDT Softworks -- 800/663-6222