Last time I checked, English Literature CLEP was the only one that's still graded (according to Excelsior's 'Student Guide and Assessment Catalog' 2007 edition).

And I believe that the reason we don't get grades for CLEPs is because the exam contents have changed and ACE doesn't have a letter grade recommendation for them yet (citing the lack of statistical data to set the cut score for grades). I was lucky to get away with grades on some CLEP exams when they were still offered back in 2005/2006 (Management, Micro/Marcoeconomics). I wasn't that lucky when I found out that Psychology wasn't graded after taking the exam (which by the way was listed as graded in the Excelsior's catalog for the year of 2005), the exam content had changed during that year and so it had become pass/fail only.

That also means that the situation can change any time and CLEPs taken in the future might (and probably should, unless the exam content is constantly changing) get back to being graded.

To play it safe, I'd always check with the advisers to make sure there aren't any changes before taking any exam.