Dear Sandy,
I agree with you -- there needs to be more diversity of platforms -- because from my perspective -- not all platforms can meet the same needs and that "illusive perfect" platform will no doubt be improved upon or new needs will have to be met. One of the main issues is "cost effectiveness" and not just focussing on technology -- but on the serving of technology for the purpose of learning and collaborative exchanges.
I'm have been really delighted with the possibilities that already exist -- but cost for education is high and availablity and access are the two main areas of concern for more massive distribution.
Although I've explored Second Life a little and am curious where it will go. Generally our various learning needs to have many adaptable venues as not one works for everything or everybody.