I wrote about Sun's Lively Kernel web browser based programming environment last month and watched this excellent Lively Kernel talk by Dan Ingalls this morning. I especially liked one point that he made: with the right architectural decisions systems can be fairly simple and still be general.
I remember getting a Xerox 1108 Lisp Machine in 1982 and I also wanted the optional Smalltalk environment which was not in the budget. However, a sales engineer at Xerox did let me use Smalltalk for a month on a trial basis. It is amusing to be able to get a smalltalk like programming environment like Lively Kernel for free that is hosted in a web browser. Something about Moore's Law and also about free software projects...
Off course, by far the best free Smalltalk experience is Squeak but Lively Kernel is still very cool, if only for its possible future use of quickly writing web interfaces using existing web services, etc.