from a browser we can make multiple ajax request. So I think that ajax is scalable. If we see website like
http://slashdot.org/ or igoogle .com, we can see that they are scalable. So its like we can make a call to multiple servers(web services) and get data faster on the client side. igoogle sometimes doesn't scale so much. If you add too many gadgets it becomes slow. But slashdot loads 10 stories per pages and as you go to the end of the page it loads 10 more stores. So it scales perfectly. Any thoughts?