Good news!
You can print without Rosetta with a PocketJet printer. Brother (who made the printers for Pentax and now just sells the PocketJets under their own Brother name) must have heard a lot of complaints from Intel Mac owners who have PocketJets.
There is now a Pentax PocketJet 3 Plus driver for Leopard and Snow Leopard. It is a full CUPS driver that supports USB or Bluetooth printing(if your pocketjet is a bluetooth model). I just upgraded from the old PowerPC driver I've been using with my mid-2009 13" MacBook Pro for the last year or so. Please note installation takes patience. Read all the instructions and readme files before doing the installation. Basically:
You download the driver from here (same file for all Pentax PocketJet 3 printers):
http://brother-printers.com/downloads/default.aspx?r3modelid=PJ523&ProductGroupID=26
Read the directions carefully.
Open the downloaded DMG file.
Plug in the turned on printer via the USB cable only when prompted (and not before).
Print a test page.
If your printer is bluetooth equipped you also have to:
Set up bluetooth pairing and a bluetooth printing queue according to the directions for your Mac OS (different for leopard and snow leopard).
Follow directions for printing via bluetooth in the manual (note the queue for printing via bluetooth is normally "PocketJet Bluetooth" where the queue for printing via USB cable is "Brother PocketJet Plus with Bluetooth"
I do not know if this driver is also Lion compatible...it definitely works with Snow Leopard.