At the bottom of http://urbanairship.com/products/airmail/ , there's a signup form - we'll be emailing that list first with early access. Or, you can email me ( michael@urbanairship.com ) and I can get you on the list.
Apple's push service has a few quirks - in addition to connectivity issues (which can definitely be numerous - thanks AT&T!), there's also a problem when passing along a development device token to a production server. They'll silently drop the connection and we won't know until the TCP window size fills up that this happened - in other words, messages can be lost. There's a feature we've implemented called push debug mode that will watch for this, but it will slow down broadcasts or large sends. We recommend having this on during testing and are working on a more automated solution. So, you could try that.
But, in general, yes, issues like this were some of the initial inspiration behind AirMail - we tried as much as possible to talk to our customers and get feedback and the product naturally grew out of hearing what they wanted.