WebOS - Are you for real ???

I found this review about different Web Operationg Systems (or Web OS's) pretty interesting . I know I know , this is where you say "A Web what ??" :) A WebOS is simply a set of applications running in a web browser that together mimic, replace or largely supplement a desktop OS environment [Its in the article anyway]
Anyway I'm impressed that there are about 15 of them around already.