According to a Reuters article, the Merriam-Webster’s Collegiate Dictionary is going to add about 100 new words in its 2009 edition, among them words which have been created by blending existing words. Some examples of these so-called ‘portmanteau words’:
staycation – a vacation spent at home or nearby
frenemy – someone who pretends to be a friend but is actually an enemy

Other new words to be added have to do with the environment (green-collar jobs – jobs that help the environment), health and medicine (locavore – someone who eats foods grown locally) and online activities (sock puppet – a false online identity used to deceive, vlog – a blog containing video material, webisode – a TV show that can be seen through a website).