Developing both web and native applications for the iPhone using Tersus is possible using any platform on which Tersus Studio can be installed (Windows, Linux, Mac and any other platform supporting eclipse).
Deployment of web applications does not require a Mac, and can use any platform, as the application is served to the iPhone's Mobile Safari browser over the web.
Deployment of native applications does require a Mac, since the application must be compiled using Apple's xCode tool and uploaded to Apple for review using a native mac utility. The submitted application is an iPhone executable, which can be installed on the iPhone natively.
Native applications developed using Tersus have been accepted by Apple, and are available from the app store - see here.
For a comparison of web and native iPhone applications see this page.
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