Quote Originally Posted by Sly
OpenAL seems to be a little-used library, hence the lack of responses I guess. It's good that you found out the answers to your questions anyway.
Not entirely true Sly, it's used quite a bit... on the OpenAL website there is an impressive list of commercial games using OpenAL. However it seems to be little-used by the Delphi Game Developer community!

Quote Originally Posted by Lightning
Q - Do i have to distribute some library(es) ?
A - Probably not included in windows
It's not default installed in Windows. There is an installer, but we always simply distributed the DLL (OpenAL.dll) with our application, looking at games that use it like UnReal Tournament 2003 and Americas Army they do the same thing.

Quote Originally Posted by Lightning
Q - Is this the only 3D audio API available on multiple platforms ?
A - Seem it is the only 3D audio API crossplatform
Not entirely true... There is another crossplatform API that (I believe) can handle 3D audio and is crossplatform. It's called FMOD and is one of the best libraries I have ever worked with, unfortunately it isn't free for commercial use, however it is free to use it in freeware. You can find more information on it here:
http://www.fmod.org/

Q - Any dependencies or other strange things i need to know ?
A - No, it seems to be able to use whatever support it finds
Depends what you want to do with it... For SoundFX it basically finds everything it needs, but for music and other extensions like EAX the user will need to extensions installed. However you can query for them so you can write your code in a way that it simply doesn't use a certain extension if it's not available or that it provides the user with an error if it's not present! However for normal playback of 3D SoundFX you won't need any extension and it will indeed use what it can find!