MacFixIt now has posted an article on this subject "How-To: Using label templates in Pages" (December 9)
http://www.macfixit.com/article.php?story=20090108215717582
But I reiterate:
"I know that you can print mailing labels from the Address Book but there is no flexibility in the Address Book labels. Try printing a full sheet with the same address on every label or printing a label in a specific position, defined by row and column, on an already used sheet with some blank labels left."
If Address Book had these features then there would be less need for mailing label templates in Pages. But even if Apple adds these capabilities to Address Book they should also make address label templates available in Pages too.