Apple quietly dropped autorun capability in OS X (it used to be part of OS 9 and earlier). The reason is that there are security concerns with such a feature. A virus could be spread using such a feature. Someone skilled could write a virus to perhaps mimic the loading of a CD volume and then release a trojan. All in all, CDs are easy to handle on a Mac, so consider it a blessing (I've never had a virus or worm or trojan and I've been on an "always on" (broadband) internet connection for about 6 years and dialup for 4 years before that.)