There is an implication of a very interesting math problem just waiting to be investigated. Unique IDs are a natural fit for something like a hash function, but

There is an implication of a very interesting math problem just waiting to be investigated. Unique IDs are a natural fit for something like a hash function, but now consider the "roughly sortable" requirement -- how about a homomorphic hash (invent one!), or a hash with a weak/predictable avalanche property. Of course, that is probably too much for twitter who just needs to Get It Done, but I find such things interesting to think about.