Well I'll be damned. Long story short: the 'bang on the steering lock until it disengages' technique actually works (or at least it did for me!).
Long story long:
My 2009 Z (only 12500 miles) has been stuck in my garage for the last 3 months since the steering wheel lock failed. I had been about to park it for the winter anyway (Calgary isn't very Z-friendly in winter), so I had time to ponder what to do about it. The car was about 7 months out of warranty when it failed and getting it out of that tight garage onto a flatbed in an icy alley would be a nightmare - so I wasn't in a great rush to go that way. I'm also an engineer with incurable DIY syndrome so I was convinced I could fix it myself. Tonight I decided I was going to open up the steering lock and see if I could fully disengage the locking pin, get the car started, and then pull the fuse as suggested earlier in the thread. But before I went out to start working on it I took one last read through this thread and looked again at the report(s) about kicking the crap out of the steering wheel lock until it let go. I have to admit I thought the chances of this working would be almost nil - and I wasn't too crazy about potentially reducing my already-low chances of getting a warranty repair. But I have some non-marring mallets and thought I'd give it a shot (so to speak). I raised the steering wheel as far as I could, felt around to make sure I was going to hit the lock assembly and not the thin cowling nearby, and starting whacking it with a fairly soft white rubber mallet while depressing the clutch and pressing the start button repeatedly. Went on like that for about a minute, but no joy. So I switched to a harder-face dead-blow mallet (16oz, I think) and tried again - banging firmly but certainly not wailing on the lock assembly. About 10 seconds in, the dash lights up and the car roars to life. Neighbors probably wondered what the heck all the commotion after that was about - last time anybody heard me making noise like that was when the Flames won the Stanley cup over 20 years ago
. I pulled the lock fuse while the car was running (I had opened that up a couple of months ago) and shut the car off. Crossed my fingers, pressed Start again, and the Z started like a charm (and no delay).
So it's just another data point, but I hope a few more people give this (literally) brute-force approach a try before shelling out $1000-$1500 for an infuriating repair. Just don't hit the thing so hard you cause damage and maybe invalidate any coverage you might qualify for.
P.S. Here's a little additional data to eventually help determine if this is a cure-all or a fluke (or maybe it just works for a particular mode of failure). The amber 'lock' warning indicator had started to come on intermittently during the week or two preceding the lock failure - I thought it was probably a fob 'weak battery' warning or something like that and foolishly ignored it. After parking in the garage one evening and noticing that the 'lock' light stayed on after I shut the car off, I tried to restart the car - but the 'lock' light just stayed on and that was the end of it: the car still recognized the fob for door lock / unlock but pushing Start did nothing (stayed on LOCK: no ACC, nothing...). I discovered I could lower the windows, but not raise them (ended up open for 3 months). I eventually gave up trying to start the car after going through every permutation of clutch / gear / wheel turning / fob inserting / button pressing I could dream up. One interesting point is that I was still able to turn the steering wheel when the lock failed: so maybe the locking pin was in an 'almost open' position and just needed a little extra agitation to finish opening up and engage the 'open switch'? Seems that a failed lock mechanism might also drain the battery fairly quickly - about 7 days after the lock failed, the battery was totally flat. I kept a maintenance charger on the battery after that to avoid damage.