I have to say YES, Zaraki's sword is in its released state. But personally, i think its in some sort of semi released state (owing to subtle differences in appearance and power released). I dont think an unreleased sword could have fought on equal grounds with Zangetsu or defeated Tousen's bankai for that matter. Zaraki might be strong but he is no Aizen.

Also, his zankpaktou may not completely look like the regular unreleased zanpaktou with rectangular hilt and all, but it doesnt have any particular unique Shikai form that we have come to expect from most shinigmai releases. I personally dont think its worn down look has anything to do with Zaraki's own persona, more a representation of the struggle between him and the sword.

As Assassin pointed out, Kenpachi not knowing its name singles it out from a typical zanpaktou release. My theory is that due the level that Kenpachi is at, he has somehow been able to draw out the sword's power partially without knowing its name through forceful means. The exact nature of these powers, we dont know yet. Maybe due to the limited state of his 'release', all it can currently do is build up on his already huge supply of reiatsu.

Based on Munsu's evidence, you can conclude that it is indeed 'released', just not in the form we are accustomed to seeing. Even a partial shikai is technically a shikai and cannot be classified as an 'unreleased' zanpaktou. That being said, I still dont think that its at the prime of its shikai release. So theres probably still some room for improvement for his shikai and bankai isnt necessarily the next immediate step after he learns its name. The complete shikai might even manifest as slightly different form.