I just happened to notice this feature in TextEdit, after upgrading to 10.5.7. Perhaps it existed before, and I just didn't notice it. But, I think it's new. Basically, multiple-page PDF files can now be viewed in TextEdit, via a scroll bar.

Normally, I will save certain emails while in Apple Mail. Save As... I normally save it as a Rich Text file .rtfd, and Include Attachments. In this instance, I attached a multi-page PDF to the original message. When I opened it in TextEdit, I was able to view all of the pages, which now has a scroll bar for the multi-page PDF.

Is this feature NEW? Or, have I missed in previous versions of OSX?