Edited to clarify since apparently I can't reply to a child comment: There are tools that require next-to-no technical expertise to passively observe HTTP sessions. There are no such tools that I'm aware of to execute an HTTP MITM without control of the network infrastructure.
I think what the original poster meant was basically just "in a situation where you absolutely, definitely, cannot have SSL, javascript crypto is an iota better than nothing, because at least it breaks Firesheep and Wireshark".