Vertically centered is a problem...you could provide a 'spacer' label above your text label. Make the spacer labels's Text color to none ... change the height of the spacer by
1)increasing / decreasing the font size
2) adding lots of text (but never showing it because text color is none)
3) experiment with Height Fill Parent perhaps
4) set the height to a predetermined pixel level ... be careful this has consequences on different sized screens.
Then you got the problem of how large is the important text ... how many lines etc. You could instruct AI to change the Height of the spacer text based on the Height of the important label..I guess there are many ways that could be done...all of them using probably complicated code...but it would work.
Try some blocks and let us know what you come up with.
Oh...someone might have a better idea, so be sure to visit here while you are experimenting. Working with AI2 layout is always a pain in the neck, however, there is almost always a solution. :)
Regards,
Steve