There are a few caveats to using the TeXshop and teTeX. Both work great (i.e. as expected). However, there are a few strange limitations.
First, Apple's support of PDF in the Quartz layer seems to be, let us say, incomplete. So if you (La)TeX your file involving heavy mathematics, the preview will probably be unreadable. Using the times package will afford you readability for your text, but that's about it. Viewing your file in Acrobat Reader or some other reader with complete PDF support will show you the missing characters. (I'm not sure about all the technicalities of this, but it seems that Quartz substitutes Helvetica for embedded fonts that are not yet supported.)
So, the PDF file is correct, but not viewable in the TeXShop viewer or the Apple viewer at this time. Hopefully Apple will correct this oversight.
Second, if you use bibtex, things become more difficult. You will have to use the terminal to bibtex a file after latexing it the first time. But, if you are converting from a classic MacOS, the linefeeds are CRs instead of the Unix linefeeds. This causes bibtex to get confused and stop processing. I had to write a perl script to convert the linefeeds, after which bibtex did ok. Maybe bibtex support will be added to TeXShop if the prof. has any interest in keeping it up.
Other than those issues, TeXShop/teTeX is quite a usable system on OSX beta. I hope when OS X final ships, the PDF oversights will be addressed, and that TeXShop adds some support for bibtex (and, while we're at it, makeindex).