There's a lot going on in the UK. ViM & Team Wilson have already been mentioned. Motorsport News seems to have got the message - most weeks there's some mention of marshalling. BMMC is doing a lot both nationally & locally, for example the recent Ginetta conflagration at Oulton raised media interest, which resulted in a small item on BBC North West (see
http://www.brsccnw.com/marshalling2.htm), & there has also been a spot on Radio Manchester as part of Stuart Jones' (a NW Formula Ford competitor) weekly motoring feature. At Oulton Park there are regular 'Walkabouts', which allow prospective new marshals to get an idea of what's involved before committing themselves.