Apple seem to have fixed the issue. In Mavericks the Cmd+ and Cmd- works in iCal 7.0 for the screen display and when printing out there is now an option on the Print Dialog to select the Text Size (Big, Medium & Small).
Bought Imac mini with 27" Thunderbolt display. Yes you can lower the resolution, zoom in, change font size in some apps, but after two days after trying to convince myself this purchase was worth the $2k I paid, I took it back.
Change the number - say to 1.25 if you don't need it so big, or increase it to 2.0 if you need it bigger. You can also change the print size in the print dialog menu - you can choose small, medium or big. Have fun!