Media attention may have been focused on the launches of iPhone 5 and iOS6  including the subsequent 'MapGate' and 'ScuffGate' backlashes  but it appears Apple itself has turned its attention to the art of app promotion.It's already understood that the Cupertino giant is keen to limit external influencers on its app ecosystem  moves to outlaw offer-wall incentivisation of note.Now it appears changes to Apple's App Review Guidelines could result in a further clamp down on third-party app promotion services and affiliate programs.Tipped off last week by a number of sources, an investigation by PocketGamer.biz has cast light on what appears to be a new clause in the guidelines that restricts apps that provide links to apps that are not your own.The wording is typically vague, but clause 2.25 appears to give Apple carte blanche to put any app that promotes titles from a different developer out of action.At the moment, we understand Apple's likely prime targets are pure app promotion services, such as (but not necessarily including) FreeAppADay, AppoDay, AppGratis, Daily App Dream and AppShopper, amongst others.Such services drive considerable volumes of downloads and are relied upon by many developers as a key part of their promotion for freemium or ad-funded free apps.However, the potential connotations are obviously far wider if this rule or further developments within the same spirit are applied towards cross-promotion/advertising plays sitting within apps.As well as the likes of Tapjoy, Chartboost, Flurry et al - whose raison d'etre is much the same in terms of driving guaranteed downloads to affect chart position in exchange for payment or inventory  self-made indie cross-promotion agreements also risk attracting Apple's attention.At present, this latter stage is very much speculation as there's no direct evidence that this restriction will affect SDK's or embedded solutions.Nonetheless, it's already accepted within the iOS development community that Apple is actively seeking to restrict the influence of all such promotional tools in order to maintain the legitimacy of the App Store charts  themselves reportedly altered during the iOS 6 update to reflect app engagement over pure downloads.Likewise, it's still too early to understand how this will pan-out in terms of the scale and rigour of enforcement - at present it appears that 'editorial-led' products and promotion services such as Pocket Gamer publisher Steel Media's Swipe magazine and Free App Alliance as well as FreeAppDaily appear to be unaffected.Indeed, Apple's action against those apps that do fall foul of clause 2.25 hasn't been to remove the releases in question, but seemingly to prevent them from updating, potentially winding down their influence over apps in the App Store.Suffice to say we'll be monitoring the situation closely and providing more information and analysis in the days and weeks to come.Do you have something to add to this debate? Have you had an app update rejected or noticed new trends emerging in chart positions?Mail us at keith[dot]andrew@pocketgamer.co.uk and we'll be in touch.UPDATE: We've managed to speak to some developers who have encountered Apple enforcing clause 2.25