Google has something similar to this at their headquarters that plots geographic search volumes on a giant globe, also, although that isn’t available for public consumption. Overall, the direct marketing applications of something like this are probably pretty low, but it may provide for interestingly analysis and it’s certainly an excellent graphical representation of the blogosphere.
Another great example of this is the 3DLiveStats.com application (the link appears to be down at the moment), which allows you to plot data from any external database on a giant 3D globe. Great for lobby displays and what not.
Video of Twingly in action after the jump.
http://www.youtube.com/watch?v=zgIT-hfgOXY