If your purchase decision for the HTC One M9 hinged on its ability to have its bootloader fully unlocked, you can scratch that prerequisite off your list. Jcase is back at it with his exceptional development skills to provide proof that he has successfully achieved S-OFF just under 24 hours after receiving it (which means a fully unlocked bootloader with no restrictions on your ability to write to the system partition).
And that’s where the story ends — the unlock method is not yet available. Jcase came right out and said there are no ETAs, and that it will likely be weeks before they’re able to release the method to everyone. They’re likely taking the time necessary to create the easiest and safest route possible, and also testing the method to make sure nothing can screw up tons of devices in the process.