Let's be clear of the problem here:
Everybody knows how to annotate in preview through either the menu or with a keyboard shortcut. However, preview in OS X Leopard is different than it was in Tiger.
In Tiger, when you annotated, a text box would appear on the margin of the document. Then, when you went to print it off, your printed document could contain your annotations. This is good if you're using, say, an online textbook in school.
In Leopard, however, your annotations appear in the margins, and are missing on a printed copy of the text. We want them to appear on the printed copy.