Go where the prospect is... The marketers' motto can be applied now also to IM softwares loved, in particular, by teenagers. Instant messaging provide great opportunities for brands that want to get in touch with people under 25, as an article on iMedia Connection explains, presenting numbers and few examples of IM used as a marketing tool.
The article is pretty good, but it's important that it has been written by a person who works for a technology provider directly engaged in the IM business.