In probably my favourite yarnbombing incident so far, guerilla knitting heroes Knitta Please have covered an old Japanese bus in knitting and parked in Mexico City. I feel some Brighton 'n' Hove-based mischief coming on... ;)
The Yarnbombing Blog
The Telegraph, 21 Jan 2009: Knitters turn to graffiti artists with 'yarnbombing'
Flickr: Yarnbombing groups