Hmmm.. good point. There is a published API in iOS for 'in app purchases' - it's supposed to be used to buy more levels on games for example) but a few apps have used it to change a 'free' version to a 'full' version. That uses the iStore payment mechanism. There's no equivalent API in Mac OS but it seems a relatively obvious move to port it across. I suspect if we don't see it before, we'll see it as part of OS X Lion.

Jon

I actually am very impressed with the mac shareware market. I treat it as commercial developers producing great products but just have trial periods to see if you want it. So far I have bought dozens of licenses. The App Store is able to open the market to these developers rather than the traditional boxed retail versions.

Pixelmator are doing just that. You can download the trial of it from their site. When you go to try and buy it through their site, they launch the Mac App Store so you can buy it through that, much like how iOS developers get iTunes to open from their site so you can purchase their app...

As I'm considering putting a few odds and ends on there, there seem to be a few issues from my perspective with demos (or lack thereof).

If I want people to be able to try an application I've produced, I don't want to have to host it myself. It's another cost, and if I'm hosting it myself then I think I may as well use PayPal for the payment of the full version and sparkle to provide updates, and encourage as many people who find the site/demo (either through the app store or however) to buy the self-hosted version. I pocket 42% more money from each sale to cover the cost of payment processing and increased bandwidth, as I'd be paying for the hosting anyway for the demo version.

I hope (and presume) upgrades will be available, and I can't see it being too problematic to port and adapt the in-app purchasing libraries over from the iOS platform to cover the application end of this.