I am one of the founders behind appsto.re. The analytics appsto.re is providing focuses on sales conversions per click for iPhone apps. Bit.ly does not do this. Bit.ly will give you referral sources but does not provide any transparency into what happens when someone lands on your iTunes app page, appsto.re analytics can tell you if a click actually converted into a sale.
OK but to clarify, a developer could just create a linkshare URL and then drop those links into bit.ly to track clicks and then conversions on those clicks?
You say you track conversions by source but I assume you have to have 1 URL per source correct? If this is the case you are no different than what I suggest above but you take a 5% cut instead of the developer getting it.
You are correct, a developer could get a linkshare url and drop it into bit.ly. Then they would have to do a lot more work to get the bit.ly click data to overlap with the linkshare data. We do some other statistcal analysis to be sure we aren't counting other app sales in your data. There is actually a substantial amount of work behind getting this to all work smoothly.
We see appsto.re as being a turn key no headache solution. We do the work of making sure things don't break, adding new analytics tools and handling all the details that it doesn't make sense for a single developer to worry about.
Shane Crawford has a great two part blog post if you really want to implement this yourself ...
No, that's not possible without tons of code to generate codes, cross reference, generate reports. appsto.re is a turn-key service, doing it by yourself is much more work than you would expect, and isn't worth it to a single or even a small group of developers.