Can any apps print from the iPhone? Preferably via WiFi...and to an Epson PX710 all-in-one in my case.
If you want to print pictures and photos, you can use Epson iPrint (there are similar apps from other printer manufacturers, e.g. Canon iEPP, HP iPrint Photo 2.0, Kodak Pic Flick or Lexmark LexPrint). For printing PDFs or other documents, the already mentioned "print n share", "Print Bureau" (both from eurosmartz) or Air Sharing Pro from Avatron could be useful.
Apple’s AirPrint Wireless Printing for iPad, iPhone & iPod touch Coming to Users in November
CUPERTINO, California—September 15, 2010—Apple® today announced that it is releasing a beta version of its AirPrint wireless printing for iPad™, iPhone® and iPod touch® to members of Apple’s iOS developer program today, and that AirPrint will be included in the free iOS 4.2 software update in November. AirPrint automatically finds printers on local networks and can print text, photos and graphics to them wirelessly over Wi-Fi without the need to install drivers or download software. HP’s existing and upcoming ePrint enabled printers will be the first to support printing direct from iOS devices.
Print n Share perhaps.
There also are a bunch of other apps for this in the app store.