There are two versions of 2600.0, one is the Evaluation, and the other is the final release build. They are exactly the same in capabilities and features, but the Evaluation build still has all the limits that previous Eval's had. The evaluation 2600.0 is final code but still contains the Evaluation limitation of 180 days.
The release 2600.0 is the same as the Evaluation version of it, but it removes all of the evaluation specific things such as a 180 day usage limit.
There is also a Corporate version, which is final code, not evaluation and it does not have Windows Product Activation.
The Devilsown ISO that is floating arround the warez scene is the Evaluation 2600.0 version that has been "patched" with the Corporate files to remove the 180 day evaluation limit and the WPA. So it is effectively the same as the release Corporate edition, but it's not a "true" final edition in that it's been hacked to emulate a final.