There are times when you want to insert tables from Numbers into Pages documents as static graphics, rather than as live, editable tables. If you wanted to do something similar in Microsoft Office, you could copy tabular data from Excel, then use Office's Paste Special command to paste the clipboard contents into Word as a picture. But there is no equivalent to Paste Special in iWork.
But there is a workaround: Copy the table in Numbers, then open Preview and press Command-N to paste the table as a new PDF. Next, copy the table (now a PDF) in Preview and paste it into Pages.
You could also use Shift-Control-Command-4 (which does a screen-grab of a region of the screen) to capture the table in Numbers, then paste it into Pages. While that works, there's a noticeable difference in quality; using Preview as an intermediary yields a much better image, regardless of image format you use for the screen-grab.
This hint actually reveals something interesting about OS X's Clipboard: It stores multiple versions of the data you're copying. In this case, it copies the data in tabular form; you could paste the table from Numbers to Pages, and the data cells would be editable. But the Clipboard also copies that table as a graphic and as text; when you paste what you've copied, the application into which you're pasting it will decide which of those forms it likes best.
This story, "Paste Tables as Graphics in IWork" was originally published by Macworld.