[micheljansen]

The London 2012 Olympic tickets are not for resale. The terms and conditions for the tickets dictate that they cannot be resold and any tickets that are resold are considered invalid. Of course they cannot possibly check that for all tickets, but so far it seems to work because I haven't seen anyone trying to resell tickets.

[JimmyL]

There are also much stronger laws (and enforcement practices) around reselling sports tickets in the UK than in the US.

[micheljansen]

Yep, reselling tickets is actually illegal and can land you in jail (or at least a hefty fine): http://www.bbc.co.uk/news/uk-england-london-19109747