The compendium says that users will receive an immortal item after the compendium reaches the sixth goal, but it looks like we haven't received it yet. Does anyone know if it is delayed, or are some people just not getting it for some reason?
No one has it yet. It hasn't been announced yet. They needed to wait to confirm that the goal would actually be reached first before working on it, and now that it has, it'll probably come in one one of the next couple of updates. My guess is the last one right before TI3, but like I said, that's just a guess. Stay tuned.
It just took a while is all. It was finally added in the July 26th, 2013 update. All players who bought a Compendium should now get a copy of The Immortal Reliquary, which will give a random Immortal item out of five newly-created items when used.
The possible items seem to be:
I just picked up Cauldron of Xahryx. Cauldron that sits on Lone Druids back, smoke pouring out the top. Sucks I don't play LD. Pretty sure it was the immortal gift, came in a box matching International colour schemes (like the compendium). And because I feel Valve are lazy with these kinds of things, everyone will probably get that, rather than a random item from a pool of new immortals.