Personally I think this is a supremely bad idea from Truphone. Yes the App Stores by Apple and Google (for the Android platform) are going to be slick, but their reach in terms of user base is going to be a relatively small number of users compared to that which could be addressed by a regular software release.
They wouldn't hear much complaint from us here regarding the poor quality of Nokia's “Download” application, but could this moved be a step too far for Truphone? It's certainly a gamble that both Android becomes a large scale platform, and the iPhone application is never 'removed' from the iPhone App Store. By relying solely on manufacturer stores, Truphone is cutting off direct access to their own customers.
Perhaps this is just a bargaining chip, to push other manufacturers into providing the same functionality as others. Whatever it is, it's a risky move for Truphone.
(More at The GTD Times).