Preview at WWDC likely in June, followed by September launch.
Apple Provides iPhone Developers with Daily Download Stats
Before today, most developers had been left in the dark about their applications performance, and had to wait until the first of the monthly reports. Apple had originally posted download numbers publicly but quickly removed this feature once it became clear that you could easily estimate a particular developer's revenue. Registered iPhone developers can find their daily stats at iTunes Connect.
Daily reports may help developers more quickly find proper price points. Larger developers must have already had access to their download stats, as Sega's president said that he expected that Sega would sell 1 million downloads for Super Monkey Ball, though no time-frame was given.
Other developers have already been making pricing adjustments due to the high level of competition in the App Store. Most recently, Pangea Software dropped the price of their Cro-Mag Rally racing game from $9.99 to $5.99.