It looks pretty simple, you can edit each row, and you can add rows, sort rows and set how many rows per sheet...here is a screenshot: http://www.flickr.com/photos/randyzhang/3275215413/

one more screenshot here- http://farm4.static.flickr.com/3475/3275225167_6f86626eea_o.png

It seems like google is testing this out now. Sometimes I got the edit, sometimes not. (yidong.google.com is the special Google iPhone optimized page url localized for Chinese iPhone/Touch users).

Yep. I'm seeing this too on the usual iPhone optimized URL.

http://googledocs.blogspot.com/2009/02/add-edit-sort-and-filter-improved.html