Apple has begun emailing registered developers with the following:
As a developer actively working with iPhone OS 3.0 beta, we would like your help in testing the Apple Push Notification service. We have selected a pre-release version of the Associated Press app for iPhone OS 3.0 to create a high-volume test environment for our servers.
Great move on Apple's part, provided they recruit enough developers to really test the scaling of their iPhone 3.0 Push Notification system. After last year's disastrous MobileMe launch, Apple needs to make sure their infrastructure is as bullet-proof as possible before they pull the push lever... even if they are planning some limited multitasking as well...
Full text after the break: