Syncing information between webapp(iphone, droid, blackberry) and the internet for users

I have a webapp that runs as a phonegap app on iphone, droid, and blackberry devices. The app saves very simple data using localStorage in HTML5. I also have a browser version of this same app that I'd like to sync with their mobile notes.

What is the best way to accomplish this? I'd like to keep it i开发者_Go百科n js and html as much as possible, but I suspect some php will be needed as well which I'm completely inexperienced in.

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Seems like storing each user's data on the server would eliminate the syncing issue. Time to get into server side programming.