2. Run Desktop-Based Applications

There will be no third-party apps to install on Chrome OS-—well, not in the traditional sense, at least (seeing a pattern here?). Applications will exist on the Web and be run solely inside of the Chrome browser, which means every web app that already exists is also already a Chrome app. So, will you be able to run Photoshop on Chrome? You’ll certainly be able to run the webified ‘lite’ version already available on Photoshop.com. Whether or not the full version will ever be browser-based is completely up to Adobe (and the limits of current web-based programming languages), not Google. The same goes for iTunes, which it’s safe to assume won’t be headed to the browser any time soon. In its stead, I expect others to step up with web-based media management apps that will duplicate iTunes functionality and maybe even improve upon it.
But, there are some problems to consider here. Because apps exist in the browser, there will be no inherently common GUI to Chrome like we’re used to with traditional OSes. The way we open documents, the keyboard shortcuts, the look of the windows and tools could wildly from application to application. What’s more, your data will be scattered all over the place. In a traditional OS, I have my pictures folder, my music folder and my documents folder, and I can use whatever application I wish to open these files. On Chrome, I’ll presumably only have access to documents specific to each app. So, if I’m creating, say, a birthday invitation in Google Docs, how am I meant to insert a photo that’s managed by the Photoshop web app?
Of course, Google could (and almost certainly will) solve these problems--a formal web-app SDK will surely provide at least some semblance of GUI standards, and it's not too difficult to imagine a cloud-based "G-Drive" storage repository, accessible from every Chrome app. But the desktop app as we know it will not exist.