Is there some way on the iPhone to trigger an auto-run of an app based on some external event such as socket/port monitoring? Sorry if this was answered by someone else. I did a search and cant find anything.
Generally that would require a background process to run, which Apple doesn't allow in the SDK. Only way I can think of to auto-run an app that Apple actually allows is to register a protocol handler for your app. So you can specify that any time an "xyz://" link is clicked in Safari, your app is launched. But that would require the user to have Safari running, or maybe a UIWebview inside another iPhone app. http://www.mobileorchard.com/apple-approved-iphone-inter-process-communication/
Well, if we're playing inside Apples sandbox then probably not. But jailbroken, the iPhone does have launchd, and at least on desktop OS X launchd appears to be capable of launching applications based on system events.