As always, Apple has provided little explanation as to why it had to remove the Push Notification feature from the latest firmware beta of the iPhone OS. Version 2.1 Beta 4 of the iPhone software says that the notification code has been pulled for "further development" over at Apple's labs, sources are reporting.

According to MacRumors, further testing will be carried out inside the company with no word on whether the push notification feature will reappear in the next beta release of the iPhone OS 2.1, or the one after that.

Apple first began offering support for the push notification service in iPhone Firmware 2.1 Beta 1. However, not all registered iPhone developers have access to some of the seeds. For instance, the first seed was only available to the 4000 developers who had been registered for the iPhone Developer Program prior to July 11th. Messaging apps such as AIM and Facebook have a lot to benefit from an enhancement like push notification. The service allows for these kinds of apps to keep themselves constantly up to date.

Version 2.1 Beta 1 (build 5F90) of the iPhone OS, as well as a new version of the SDK, were seeded to developers in July. The new one (allegedly) included new Core Location features, suggesting turn-by-turn GPS as a possibility in the near future, cut and paste support, and more. Other details regarding the first beta release of firmware 2.1 included references to a "mobile radio" function. According to the reports, the feature would indicate Apple's support for native Internet radio, instead of through third-party apps.

It was later revealed that iPhone firmware 2.1 only contained bug fixes and an implementation of the Apple Push Notification Service API. "This is the second beta of the iPhone SDK targeting iPhone OS 2.1, including bug fixes to iPhone OS as well as an early implementation of the Apple Push Notification Service API," Apple described the new beta release. "This API is not yet integrated with a live push server."

Also included were references to a new iPod touch, which suggest that an upgraded model is due out by the end of the year.