The last (or next to last, impossible to know) Google service/tool is "Google Blog Search". The linguistic interest? Well, possibly it can be a way to search texts which tend to be more informal. The bad thing is that even blogs are getting spam or being put online only to advertise porn/easy money, but that is some noise you have to deal in any case you want to get usage statistic from the web. I'll start to experiment on it soon and, if I remember, I get back to report how it goes.
Another point erlated to the blog search is what are Google plans with it? Word on the net is that Google might eventually get rid of blog content in the main index. The reason for such a move is that blogs are supposedly polluting search results because they tend to keep talking about the same stories and that schews Google's algorithms too much. I have no idea if the move will ever happen, but I see that more and more search is becoming a specialized business, what really sucks. I mean, Google Scholar is great, but who knows that if we will need Google Math, Google Physics, Google Language (yeah, right). Problem is, for how long is it gonna be possible to get good search results with so many billions of indexed pages? But I will not make any prediction.