Jacques Distler: To borrow a phrase from Samuel Johnson, “… like a dog’s walking on his hind legs. It is not done well; but you are surprised to find it done at all.”
Jacques has a way with words. It does seem to me that collaboratively editing complex formulas and simple diagrams would be one of the use cases for Google Wave, yet I can see the vast number of separate problems that need to be solved in order for this to be addressed ubiquitously (i.e. using only the browser that the user happens to have in front of them at the time).