Hey Hey Hey! It’s Google Spreadsheet~
Here is my five minute review. I got my invite so I just had to take a few minutes to play with it.
Works on a Mac in Firefox and seems quite nice. No Safari support. Scrolls better than iRows and has a very simple and clean design.
I don’t see any ‘link’ abilities though or sheet tabs. You can freeze rows/columns and change the color of text and do basic formatting.
All the PC shortcuts are here, no Mac keyboard shortcuts though.
No Spell checking.
Sharing is with specific people only, not the public.
It seems to get confused when I rename a sheet or delete a sheet.
It’s new so it’s quite basic but a nice start.
That’s all I have time for now. 
5 minute video tour:
http://blogs.law.harvard.edu/teadams/2006/06/06
Hi! Have you seen EditGrid also?
There’s a comparison between it and google spreadsheet here:
http://www.editgrid.com/tnc/pkchan/EditGrid_v._Google.
You may wish to take a look!
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