I wonder if there's any clever trickery can be done here to let web services get access to iCloud APIs. (I suspect not, due to the authentication nightmare that would be involved)
Apple's apps are at a real unfair advantage, here.
Say I wanted to replicate Apple's Notes app: I can write iPad, iPhone and Mac apps that all share the same storage (and update in the background without the app running). But there's no way for me to create an equivalent of icloud.com that lets users edit their notes on the web.
You will be able to do that with Objective Cloud. We will have a distributed storage service that you can use. You will be using Core Data like you are used to.
Apple's apps are at a real unfair advantage, here.