With the dust only just settling after the launch of the Apple iOs 4.2 upgrade, the company looks set to roll out yet another update, unsurprisingly called iOS 4.3.According to T3, Apple is due to host an event on December 9th, which is expected to showcase the iOS 4.3 upgrade. No one is quite sure what this will include, after all, iOS 4.2 landed just days ago. But the one thing widely expected to be highlighted is a revamped app store that will allow apps to be sold on a subscription basis.Those rumours have been given weight by The Guardian. We heard some time back that The Guardian app for the iPhone will be switching to a subscription model. To do that means a change to the app store. The Guardian is bringing its new app to the market before Christmas, so if you want to put 2+2 together, the resulting '4' is almost certainly an app store update as part of an iPhone OS update.So keep an eye out on Thursday for the announcement, all being well. It might just be a tweak...or it might be something altogether more impressive for both iPhone and iPad.