OWA 2010 and prior is considered non-extensible as far as Microsoft is concerned in the area of doing single-sign-on programmatically. The exception to this would be when a person is in-network and uses their existing network credentials to access OWA through Windows Authentication. Please understand...

I have not seen any examples of using OWA parts in an iFrame. However, I wrote such a sample recently and wanted to share it. The full OWA UI in an iFrame is not supported and its expected that doing so may fail at any given point and at different points depending upon the service pack and hotfix...