A pap test only looks for the presence of abnormal cells on your cervix. Some of the newer pap tests also combine it with std testing but even that's of limited value. So yes indeed you can have a perfectly normal pap test and still have many std's :(
If you want to know what your std status is you need checked for them seperately. www.ashastd.org has terrific info onhow to get tested for std's to learn more.
http://blogs.webmd.com/genital-herpes-intimate-conversations/ check out the post there from last february on the pap test and herpes for more info too.
grace
A pap itself does not test for STI's. A pap is to test for cervical cancer so it can test for HPV. The Dr doesn't check for infections unless there are some suspicions of symptoms, unprotected sex, or vaginal infections. So you can be cleared of STI's and have an abnormal pap (even with STI testing or without). You can also have a normal pap smear result if you have STI's.