Twitter is branching out by enabling users to tweet from other websites including Amazon, Bing, Citysearch, Digg and eBay. The new platform that enables this is called @anywhere and Twitter announced it at the South by Southwest Interactive Conference in Austin last month. This could have significant consequences for marketing, as friends can tweet about their online product purchases and recommend products and items even more than they do now.
Mashups like this are the future of the internet. Converging technologies of texting, email, mobile smartphones and software as a service technologies like Twitter are where everything is heading right now. You will be seeing alot more of this sort of thing.