I wondered that too but have no information.
At WWDC, I listened to Apple representatives make some excellent points about taking the time to build a 100%-compliant Aqua application, and I think all developers need to look beyond the code and listen to what the folks at Apple have to say
Okay, I just told you what Apple wants you to look out for with window positions, but in the real world, not everyone uses the hiding feature of the Dock, and it is unrealistic to be able to predict where each user will place their Dock at any given day or how large they will have it. However, you can build a feature into your application that allows spacing for the Finder. You can give users the option of where to position their windows and what area of the screen not to cross. I know that BBEdit provides me with this feature, and I wish more developers gave me more control over my windows.
But limit your animations to whatever is required to communicate the necessary information. Avoid annoying animations that discourage ease of use. Ask yourself, "What do I need to show the user, and what is the cleanest way possible to achieve that?" A good example is the Mail application for Mac OS X. Whenever a new message arrives, the Dock icon changes appearance to indicate a changed state.
This is the first thing your users see, and probably the single most important visible part of your application. It is the first chance you have at making an impression and the best chance to help establish your brand.
Help! Did you include help tags in your applications? (I'd be lost without them.) Also, be sure to take extra time to develop your other help files. The Apple Help Viewer supports HTML, QuickTime, and also AppleScript. Take advantage of it! There isn't anything I hate more than going to the Help menu and finding there isn't any help.
Adopt Sheets. I really like the use of Sheets in OS X. The use of Sheets lets me know which window my dialogue belongs to without hijacking my system.
The simple fact is that, when all other factors are equal, where will consumers spend their money? I believe that in the long run, the best looking, easiest-to-use applications will also be the most successful. I think that's why Apple encourages developers to write programs that are 100 percent Aqua-compliant.
For my Paint application, I created a series of icons to simulate a rendering algorithm. While the application is performing this CPU-intensive task, you can always see the status of the document by the icon changing in the Dock.
Whether native or not, this is obviously one of the first steps on your way to OS X. Keep in mind that often, the functionality of your code has a lot to do with how your interface is designed. How many developers have come up with great functional ideas from working with their interface or looking at their competitors'? Start working on your Aqua compliance from day one. Don't wait until the last minute.
Adhere to File Locations. Make sure that when your users save documents, your application knows where to put them and also gives users flexibility.