In the last day, Apple has started approving quite a few "new" browsers in the app store, seeming to contradict their long-standing "duplication of functionality" prohibition. The catch? They're all Safari at heart.
The chromeless Edge, vibration-countering Shaking Web, privacy-inclined Incognito and enhanced-tab WebMate browsers all claim functionality that you can't get with Mobile Safari, but they're all based on Safari's version of WebKit. In a sense, they're like browser extensions, but which can only run one at a time and as completely separate apps.
This isn't an entirely new concept, as many iPhone apps already call on Safari's rendering engine (the NYT, AP and USAToday apps, the name a few) to display content. The difference now is that these browsers are marketed as browsers, and could serve as total replacements for the stock app.
The approvals do represent some leniency in Apple's app approval policies, but don't necessarily mean that the company is moving any closer to approving browsers based on a different engine, namely Opera Mobile and Firefox. Assuming these approvals hold, though, we could soon see a huge expansion of Mobile Safari's capabilities, albeit through awkward, redundant copies of the app. [MacRumors]