I see. Now that you mention it, Apple's own keyboards don't even have a num lock key. Well they do have a weird key in the usual num lock key position, but it doesn't do anything in OS X. Update: apparently the key above 7 on the num pad does work as numlock when the Apple keyboard is connected to a computer running Windows/Linux. Update 2: aha, in OS X that key is the "clear" key. Clears stuff when in the Calculator app for example, but doesn't do a thing in a text editor. Update 3: in Excel one can use Shift + clear to enable/disable num lock, in Excel it will show an indicator next to the text NUM at the bottom of the window. I just tried it out (found a full size aluminum Apple keyboard somewhere) and it works. It's quite weird overall.
So yeah, I guess the non-working num pad on the TE seems to be OS X's fault. Kinesis proved it can be worked around though.