People that are fascinated by Apple usually don't look around for other things, they like the polished products that just work. But for other people and technologists it's not like that. We usually are looking for the best tool for the job. So my point here is that not many Apple fans even heard of Chrome OS. Yes, they probably heard about Chrome browser (and this was very smart move by Google by the way, first to release the browser by the same name for many reasons, but one reason is that people are getting used to the Chrome web experience).
Anyways, the question that I really wanted to address here is: was the development of Chrome OS and the Chromium project in general a response to the iPhone OS thread and the coming (now released) iPad or maybe it was exactly the other way around?
So Google started actively working on the Android OS about 2 years ago while iPhone was already available but doing the first baby steps. The pace of development of Android was quite fast and at the moment these rival operating systems are somewhat comparable in futures stability and usability. Some are lacking on Android and some are lacking on the iPhone. Last year Google started working on the Chrome OS which is essentially an operating system inside the browser and just about a month ago Apple released the iPad to the public. While there are already a few tablets running on spin offs of Android OS, Google is rumored to be soon releasing its own tablet and what it will run is yet unclear.
Anyway however, it seems that Google is targeting the same space that the iPad does right now with its Chrome OS. Simple operating system. Or is it an operating system and can it be compared with the iPhone OS which is actually an operating system. Very limited at that but still. If the Chrome OS would be the strictly in browser OS it is questionable how it will stack up against iPad. Users are used to having free access to their file system and being able to install software rather than use webapps. In that sense the iPad is revolutionizing and laying out the ground for the change of computing paradigm we got used to so far.
It is not clear what came first (as the concept) and what was developed first but it would be sure very interesting to watch this evolution of computing in the near future.