So let's see...
There are in fact sourcing and sinking data, for both pin types, so that's neat. It's... well, I guess it's not necessarily full CMOS output, but it could be, which would get you a nice full waveform (inactive rows held low, inactive columns held high). If they aren't driven full wave, but gated to be only open drain (P or N), and both pin types can be configured either way (noting that the P/N drivers themselves aren't equivalent, with the row N's being weak (16mA) and the com N's being very strong (350mA)), then that would be helpful for adding drive transistors, which of course invert state; and also for using common-anode displays I suppose (with or without external transistors).
It should be available on both pin types then, not just the coms?
Tim