Right, you had a question. We don't think you can acquire a trademark for the blog because we assume it's your friend's blog, not your wife's. If that's not the case, and your wife is co-owner of the name, the parties can register the blog name by following these instructions. Still, that will only get you the right to stop others from using a similar blog name; it won't give you the ability to stop copying of the blog's text.
Copyright's where it's at. Your wife already has the strongest form of protection -- copyright. She gets it automatically whenever she posts an entry. She can augment her rights by filing for copyright registration. Registration has some great benefits and soon we'll be posting an article on how to register blog articles (though this entry may help, for now). Assuming there is no written agreement to the contrary, your wife owns the copyright in whatever she creates. She impliedly gives her consent for publication in the blog, but not for anything beyond that use. So, if the blog's administrator/owner uses your wife's entries for some other purpose, your wife can legally prevent that use if she chooses to flex her copyright muscles. For the future, perhaps she may want to create a simple agreement explaining how any uses are to be handled -- that is what can be reproduced by the blog owner and her compensation for that use.