1. You'll be surprised by what you can do with AJAX...stay tuned.
2. Apple has intentionally and deliberately closed off 3rd party apps. It was closed in January. They said so. it wasn't in the cards. and i'm betting at least on 80%+ odds that there will never, ever be a general developer sdk.
They need to do two things:
-Allow users to load web "apps" on their iPhones (basically mini-site bundles just like Dashboard widgets)
-Provide some mechanism for local data storage (WHATWG/HTML5 etc)
If those happen - and they probably will - there won't be a need for a true XCode SDK.