Any iPhone owners out there hoping to get their hands on the fabled 'push notification' ability for third-party applications next month are in for a let-down after Apple decided to delay the feature.

The news comes as the SDK for beta 4 of firmware 2.1 reached developers at the weekend, revealing plenty more than the usual bug squashing of previous betas.

Broken promises

Even though Apple promised at WWDC in June to grant software developers the ability to push notifications to their applications even when they aren't running, it has decided that the feature needs more work.

So, until it does arrive, users of Facebook, IM programs and the like, will still have to manually log in every few minutes to see what's new. Or they could just get a life.