The true road warrior often needs to carry a printer along for knocking out those hardcopy prints of documents or even photos and there are not that many printers to choose from that are truly light, small and capable.  PC World has published an article that gives a brief overview of a number of full function portable printers that sheds some light on what printers are available currently.  I use a Canon i70 which has served me very well and the newer i90 mentioned in the article gets good marks.  The article also covers some printers that are not true portable printers (meaning no battery options) but that are small and light enough to be carried on trips.