This is an '04 XC-90 Twin Turbo. Never had a problem turning the key before. Key inserts easily, turns smoothly to position one. Electronics work, steering wheel unlocks, windows roll down, AC comes on, etc. But I just can't physically move the key beyond position one. It feels jammed or frozen. Car is in park, steering wheel locks and unlocks easily. It started perfectly 12 hours ago, and I've driven it every day for the past 2 year with no problems. I've tried the spare key as well and no luck.

Is it the tumbler? Ignition disabling system gone haywire?

Any thoughts would be greatly appreciated.

I haven't worked on one of those new fangled pieces of junk yet. If the steering wheel cover comes off the column to expose the electrics, do so. Then remove the electrical part of the ignition switch, and try your key again.
I suspect the electrical portion is kaput and not allowing the key to turn any farther.

Klaus