Whats the difference people, if your 8 certified your 8 certify, Oracle is not like Microsoft, with Oracle once your certified you don't lose it. If you happen to miss an release and don't upgrade and have to start from scratch thats your fault not Oracle's, they give you plenty of time to upgrade.
i.e Your 7 certified missed the 8 upgrade and it gets retired and you have to start the 8i track from scratch.