you can only see pagination in Numbers 3.2 when you select the menu item "File > Print...". This is departure from the way Apple designed Number '09.
You can provide feedback using the menu item "Number > Provide Number Feedback"
Ian has written a user tip:
Instead of Menu > File > Export To... > PDF, do
Menu > File > Print... to get Print Preview.
A large table in Print View (zoomed out for a smaller screen shot)
The page breaks are inserted.
The Print Setup panel on the right allows you to set the page margins (drag the panel up to see).
Now click on Print... to get the Print Dialogue
Click on PDF (lower left)
Save as PDF.
Here is the PDF (zoomed out for a smaller screen shot)