The Cookie Cutter Guide to Charting in the App Store
taptaptap.com
taptaptap.com
Not explicitly mentioned in the linked article is that the more gorgeous and non cookie-cutter your app's UI is, the better a chance it has of breaking through into the top charts. How else to differentiate your app from the standard UITableView/UITabBar drones out there? The best looking iPhone apps combine good looks with focused functionality.
Weightbot
Note: I've bought the MacHeist bundle before and I did recall getting the Voices launch email blast (and GMail search confirms) so I assume it was sent to Tap Tap Tap's (600k strong?!) mailing list only.
I've worked on some MacHeist developer relations projects before, and one of the benefits is the massive email list. Dan Grover, the developer of ShoveBox, participated in one of the bundles recently, and sums up his feelings in this comment: http://news.ycombinator.com/item?id=945891.