iRows - a web-based multi-user spreadsheet

Google's purchase of Upstartle, the small company behind the useful and successful web-based word processing tool Writely has caught a lot of people's attention, with talk of long term trouble for Microsoft. Will the similarly useful web-based spreadsheet tool iRows be next? Perhaps not, because you'd think that a spreadsheet is something Upstartle is already working on.  To get a clearer sense of what web-based applications like Writely and iRows have going for them, it is worth reading this iRows summary. If readers have good examples of the use of tools like Writely and iRows in online learning, please use the space for comments. (For some "insider" views on the take over, see this piece by Peter Rip.)