pete@cat5org.co.uk declared for all the world to hear...
> Yes it will still work

No it won't, it will have been automatically blacklisted.

> There is nothing to stop your friend taking it to a shop and having
> the IMEI changed for a tenner first.

Thats a very broad statement. Firstly, on some phones it's actually
impossible to change it, and secondly to find a shop that would do it
and openly advertise the fact would also be impossible as IMEI changing
carries a maximum jail sentence of 5 years.
--
Regards
Jon