In Support, neither Apple Mail nor Addressbook are listed on OS apps. And if you go to Feedback > Product Feedback, there are 31 apps listed, but Apple Mail and Addressbook are not listed there either. Mac OS X is, so you need to use that for these apps.
But I think the lack of listing is not so bad, but is indicative that Apple doesn't seem to embrace these apps the way it does it's other OSX built in apps. They are basically good apps. I use them as my default apps along with iCal in order to always be in sync with the latest OSX release/update. I used to use 3rd party PIM apps but then had to always wait until they released their update to be in sync with the latest Apple OS. After awhile I realized the smarter approach was to use Apple's software as much as possible since they will be designed to work with the latest OS upon the release of the latest OS.
But the built in apps: iCal, Addressbook and Apple Mail, while sufficient, are not full featured robust apps like their 3rd party competitors. I have to assume some this is financial since they are included in the OS where as 3rd party apps cost $40 and up, plus upgrade costs after a certain cycle lifespan.
Personally, I never want to use a calendar, contact manager or email 3rd party clent again so that I am fully in the Apple family with hardware and software all made to work together.
If the reason these type apps are not more robust is because Steven didn't feel we needed more, or because there are only so much design and programmng resources Apple can apply to essentially "free" apps, I would welcome a paid for "Pro" version of these apps to pay for more features.
Example: while iCal and Addressbook sync with all your devices, Apple Mail doesn't. Now that I have a new 2nd computer (MBP), I would REALLY love it if all my folders on the left column were identical on both my Mac Pro and MacBook Pro.
There are other feature requests I would make, and bet you would too.
I hope this is helpful to all and to Apple in terms of making their indigenous apps more robust for us, listing them in the OSX apps list in Support and Feedback and embrace them as signature Apple apps fully supported, developed and proud of.
Just my opinion.