As a N900 owner, I often wonder about this ...

What does an opportunist thief do with a codelocked N900 anyway? I assume that your average robber isn't a linux guru, and probably hasn't read the TMO flashing wiki, so I guess all they can do is take it to their local (dis)reputable phone repair shop and ask them to unlock (i.e. flash) it?

If so, will such shops normally do so "no questions asked" or is it difficult to do without proof of ownership even in a dodgy place?

If it's easy/cheap to have the phone flashed, then - no matter what your preventative measures were - it boils down to timing: Do you notice it's been stolen & can you then react quick enough to make a diference before the thief has flashed the phone and disapeared for good?

Just for fun, what would you do in the scenario where you had your device stolen from your table at a local coffee shop while you were on your own and without another phone? I know about SMSCON, iamhere etc. but they're just tools, I'm asking how you'd actually put them to good use with the aim of gettign your phone back unscathed.

I have a reverse ssh tunnel always open on N900, so I'd do the following:

1) quick check in case any one in the shop had a laptop they were willing to let me commandeer
2) assuming not, hot foot it back to home (or to nearest ssh -enabled device I can find)
3) ssh into my home server and then connect to the open reverse tunnel
4) run a location script to get GPS fix & look up on Google maps
5) $ TIME=600; while [ $TIME -gt 0 ]; do espeak "you stole this phone you ****ing thief! I am the owner; I know where you are and I'll see you in $TIME seconds"; let TIME-=5; sleep 5; done
6) phone-control --capture ~/thief.jpg
7) /usr/bin/dbus-send --print-reply --dest=com.nokia.image_viewer /com/nokia/image_viewer com.nokia.image_viewer.mime_open string:file:///~/thief.jpg
8) phone-control --dialog "THIS PHONE IS STOLEN. DO NOT ASSIST THE THIEF - POLICE EN ROUTE. IF Found, please call <my_home_number> to claim a £50 reward for safe return"
9) phone-control --unlock; sleep 20; phone-control --lock
10) phone-control --speakeron
11) phone-control --call <my_home_number>
12) answer the call & shout down the line "OK, I'm about to call the cops, but if you go back to the cafe you stole the phone from, and hand it in as lost, I won't bother - it will save me some hassle. I'll be tracking where you go next, it's your choice!"
13) phone-control --endcall

for the less techy, the above would: connect me to a teminal on my N900 from my PC; Get the thief's location; Start the phone shouting every 5 seconds (in a loud electronic voice) that it's been stolen ; Wait for thief to pull phone out of pocket (to try and stop the shouting) ; Take a photo of the thief; Display the photo fullscreen on the N900 ; Put a banner over the photo to confirm he phone is stolen ; unlock the phone briefly (so the thief can actually see his mugshot!) then lock again ; make the phone call me at home so I can tell the thief to return the phone to the cafe as lost, then hangup on him.

Then, continue to follow him on GPS to see if he (a) goes back to cafe (b) drops phone where it is or (c) continues on

if a or b, go retrieve! If c, then really do call the cops, explain the situation, get the cops non-emergency direct callback number and then force the N900 to call that number on speakerphone (remember to have recaller enabled to auto-record calls, that is one call recording I'd enjoy replaying) :-).

Any other scenarios you can dream up that are more likely to succeed in a safe return and without resorting to the carrier to block the phone?