I admit it looks quite cool, but I've got absolutely no doubt at all that it would never actually be used (in fact I'd quite like to see it happen just to see the logs of how few people used it).
Besides, it would probably look far less interesting for StackOverflow - just a big C# in the middle.
Also, you could make it yourself using the creative commons data dump.
UPDATE: To satisfy my own curiosity I created a quick tag cloud using the first 7-8 pages of tags on StackOverflow using this nifty looking tag cloud (looks cool, but its even less useful than the above tag cloud as it has no text until you hover over it)
Anyway its here