For Google Blog Search you can create EXACT searches by adding %22 (quotes)so for Las Vegas (all words) would be...
http://blogsearch.google.com/blogsearch?hl=en&tab=wb&q=las+vegas&ie=UTF-8&scoring=d
For Las Vegas (Exact) would be...
http://blogsearch.google.com/blogsearch?hl=en&tab=wb&q=%22las+vegas%22&ie=UTF-8&scoring=d
Hope this helps.
Blessings,
Ed