Things that popped into my head
1. Dumping of WMI - Great, I hated the integration, it sucked. Especially hated the mailbox reconnect because of all of its issues. And the bugs in the Exchange_DSACCESS class making it nearly worthless for monitoring what DCs are really being used.
2. What about management from older platforms and non-MS platforms? Say provisioning from UNIX/Linux? Not everyone is entirely MS and in fact the more MS has tried to push that way the more larger orgs have pulled away from it (think "avoiding pigeonholes"). The DS team has recognized this and is working towards considerable platform interconnectedness. Should be possible to mailbox enable a user without having to do it only from an MS machine with the latest and greatest tools. This is a very basic provision process.
3. If MAPI is going to still be around and used, lets see updated Docs and books for it. Kind of sucks to have to go back to 5.5 docs for instance to figure out how to enumerate rules programmatically on Exchange 2003.
4. KEEP IN MIND ENTERPRISE COMPANIES! We do things differently in many cases. We do not have a single domain all of the time. We have multiple domains and forests. A machine having to be a member of the forest that Exchange lives in is quite a hindrance on support especially if managing multiple Exchange Orgs either as a service provider or just because your large company for some reason has multiple orgs.
5. I noticed in the slide deck the get-mailboxstatistics cmdlet, I assume that you can pass more params in if you only want some of the info and not all of it?
6. Ditto on the mailbox create with new-mailbox, I didn't notice where you specified server for the task, I assume you can or are you expecting sgdb to be a unique combination across a forest and across multiple forests if using exchange resource forests, or managing multiple forests, etc.
7. Finally, if you are doing something that leverages something lower level, go directly from the level you are working at to the base level, don't go down to one level and let it take you to the next and so on and so on. An example here is the .NET stuff for accessing AD in 1.0 and 1.1. Look at what is done for 2.0 and an interface that goes straight to LDAP and not through ADSI. This gets you away from worrying about bugs in each of those levels making your components worthless. I am a DS MVP and strong MS proponent but have no desire to use the .NET stuff from what I have seen from the DirectoryServices side. I am perfectly happy with LDAP and don't have near the issues people do using ADSI and the current .NET DS stuff. Couple that with working with many of the largest companies in the world and knowing that provisioning is often not going to be from MS platforms makes me concerned by what I see here.
8. Keep in mind that many people won't or can't jump on to E12 and its new tools right away, I have several Fortune 50 or bigger companies as customers who are stilling running Windows 2000 and Exchange 2000 and not looking to jump for at least a year. I just read in an article about MS turning 30 and SteveB and how he drives a 7 year old Ford to work everyday, it made me laugh. How would he feel if something broke and he was told, we can't help you, you need to upgrade to Ford Car V2006 even though your current version does what you need. We would certainly do that if someone complained about how broken Windows 98 was working...
joe