I like to interchange whole fat Greek yogurt for sour cream. As DonnyG points out, the higher fat content makes for a moister cake. Rivka has an amazing maple yogurt pound cake on this site.

I also use yogurt interchangable with sour cream and buttermilk in cakes. Yogurt makes a really nice cake to me.

Ah, I missed the key word "greek" yogurt. Which I'm sure will not only match but exceed the fat content of sour cream. Which can only yeild a more moist cake.

Yes, I as well do this but the thought is that I'm matching the fat content. If your doing it to lower the fat content expect it to maybe be a little dryer.

I interchange the two all the time.