As a reminder, wikiCalc isn't just a browser-based spreadsheet. It's one that supports simultaneous use by multiple users the same way a typical wiki allows the same thing for text-based Web pages. Earlier today, in advance of tonight's Cambridge geek-eat (organized by Dave Winer) where a newer as-of-yet-unreleased alpha version of wikiCalc will be demonstrated, Bricklin gave me a preview of how much better wikiCalc gets once it gets cleaned up with AJAX. It was pretty shocking. Not only does it do all the things that wikiCalc alpha 0.1 did (basic calculations, Web-based collaborative spreadsheet development, support relatively standard wiki markup inside of cells, and offer fairly granular control over multi-user access), wikiCalc, much to the chagrin of those who are saying it can't be done, now feels much more like a typical spreadsheet like Excel than it did before.
For example, with AJAX, wikiCalc now watches for any keyboard or mouse events and responds appropriately. Right arrow. Left arrow. Up. Down. It all works. Not only that, just like with Excel, when you leave a cell, that cell and all the other affected by it (and only those affected by it -- good for recalc performance) automatically update (before AJAX was added, this required the Web page to be refreshed).
Said Dan via email regarding his AJAXizing of wikiCalc:
It doesn't really show much is screen shots are static and AJAX is all about interactivity, but here's a screen shot I took from today's preview.