GameBoy Advance Emulator coming to iOS 7. No Jailbreak required

Yes jailbreak required.

From site: How can I install GBA4iOS? Unlike other apps for iOS, you can not install GBA4iOS from the App Store. Until GBA4iOS 2.0 is released, you can download version 1.6 from iEmulators, run by Start3rs, an awesome group of people who are beta testing GBA4iOS 2.0. To install, open the link on your iOS device, and follow the instructions at the top of the page.

It seems like they are using iOS Enterprise distribution. It'll work fine until Apple finds out and blocks their signature and shuts down their developer account.

Edit: Also be adviced that this means Apple hasn't screened this app for malware and privacy issues.

I guess this means it'll be browser based, but the screenshots make it look like a native app. Hmm.

A wrapper maybe?

Even if it's only a wrapper, Apple may not approve it.