Like Nicholson emailed me a link to this interesting case study in user-led branding. The cease-and-desist part gets very postmodern I think.

Brandjacking Burger King on Twitter - Lessons Learned @theBKlounge

This is Luke's synopsis, which I can't beat:

punter goes on twitter, claims to be Burger King, follows and extends BK's brand ethos, sells about a million burgers, sends CEASE AND DESIST to another BK impersonator, is left alone/ tacitly suppported by BK, and hailed as one of the best official corporate uses of social media by mainstream press!