No, they are not. There are even two versions of Octalink that are not compatable with each other.
Adam
[edit] Hey, hope you aren't offended by this, but by looking at the other threads you started, you really should search the forums before you post a Q. I searched "isis octalink" and found three other threads that would have answered your question.
http://www.bikeforums.net/showthread...=isis+octalink
http://www.bikeforums.net/showthread...=isis+octalink
http://www.bikeforums.net/showthread...=isis+octalink
The answer is also online at:
http://www.isisdrive.com/isisdrive/faq.htm
No biggie, sorry bout the rant.