Lion no longer installs all the printer drivers out of the box, I guess to cut down on unnecessary downloading from the Mac App Store. On 10.7.1 it wouldn’t let me add a printer with the error:
The software for this printer is currently unavailable. Please contact the printer’s manufacturer for the latest software.
However by running Software Update (from the Apple menu bar) after connecting the printer, it successfully downloaded the correct drivers. The Add Printer option then automatically installs the printer once selected.
Update, thanks to Rob in the comments for his suggestion that seems to be helping a lot of people:
If running Apple’s Software Update doesn’t fix it for you, open Preferences->Print & Scan and then hit ctrl-click (or right mouse) over the list of printers and select “Reset Printing System…”. That will uninstall all your printers but then I was able to add the Officejet by clicking the “+” button and the error went away.