This is one of the easiest things to do and can be done with any theme out there. I’m going to assume you want an ad filled landing with lots of links to the blog etc. What you need to do is create your landing page with the original blog files, then you need copy all of them to a new sub directory. I am not sure exactly which have to be copied, so it is easier to simply copy all of them. You will want to change the stylesheet reference to /newsubdirectory/wp-content/themes/ sametheme name/style.css
You can make what ever changes you want to the new theme, but you have to keep the directory name the same. I have played around with this a bit and am pretty sure this is How Darren Rowe of ProBlogger does his. You will notice when you go to the blog link and click on a permalink it shows up as a root directory file.
