OK, that wasn't what I assumed at first, but clear now. Hmm, it's easy to do if you just have one line of text. You just set the line height to the same height as the element (44px). So ideally the menu links would expand to the width of the text.
With multi-line text, it's harder, but is doable. Have a look at these two demos by Rayzur:
Vertical Aligning Text within Lists Items
Vertical Centering Random Wrapping Text Lines
I like the first one in particular, but it won't work in IE < 8.
EDIT: Duh, just checked in IE7 and it does work. Trust Ray to cover all bases!