iPhone Multitasking and Background Updating

Marco Arment proposes another iOS multitasking service for registering to check for updates with a server periodically. I said I was looking for this in my original iPhone background processes list. Arment says:

This would allow Instapaper to download updates in the background, and would also greatly benefit RSS readers, Twitter clients, chat programs, weather and news widgets, and a huge number of other applications

Such as Notes, Calendars and Mail applications. (I don't know if third party Mail and Calendar apps are allowed. I'll have to check if there are any.)

Simplenote would really benefit from this.

Update

There do seem to be some third party email and calendar apps.

There is an app for accessing a Hotmail account. I’m saddened by the app store review saying how the writer felt trapped by the iPhone email app. It is Apple’s app that supports the flexible IMAP standard and Hotmail which does not.