Yes, unfortunately Oracle are still using System V semaphores on Solaris despite the availability of POSIX semaphores. Have a look at Communicating the POSIX way for some interesting reading on POSIX semaphores under Solaris.

As you point out, Oracle have discontinued the Solaris post-wait driver in Oracle8. I'm not sure why, but I presume that there was a good reason. Post-wait drivers are still available on some other platforms.

I was interested in your System V Semaphores vs. Posix discussion. But I have found out to my great disappointment that Oracle 8.x has obsoleted the POST_WAIT_DEVICE and USE_POST_WAIT_DRIVER parameters (According to OraDoc). Assuming you guys already knew this, did Sun and Oracle figure out the bugs/limitations and create a work-around?