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.

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