On a more positive note, high availability features are hugely improved in Exchange 2007. You’ve got an LCR (Local Continuous Replication) option that simply copies the entire Exchange message store database again on the same machine. However, Microsoft says that LCR isn’t an exact mirror of the repository, as it would be if you used disk mirroring, for example. Instead, LCR uses Exchange APIs so that corrupted data isn’t copied over. This is a decent option for small businesses, and SP1 improves on it by supporting replication to a separate server without requiring clustering.

Enterprises will want to examine CCR (Clustered Continuous Replication), which allows full message store replication to another server node on the network. What’s nice about this feature is that building distributed fail-over architectures now comes with Exchange out of the box. You can even combine LCR and CCR to double-protect critical servers. Frankly, being able to build this kind of reliability straight out of the box makes the 2007 upgrade worthwhile all by itself.

Now for our favorite Exchange 2007 feature: Outlook Web Access 2007. Forget your Daddy’s OWA, because 2007’s version is the one to beat. The new OWA uses Microsoft’s new Web service development tricks to excellent advantage, providing a UI that’s the functional and (almost) visual equivalent of Outlook 2003. Microsoft’s stated design goal was that users would be able to employ every aspect of the Exchange-Outlook relationship via OWA, not just critical features. Admittedly, opening that much of the internal workings of Exchange to Web service developers might give some admins the security willies, but Microsoft claims that controls are in place to protect back-end data. Time will tell on that one.

The space-time continuum has limited us here to only a brief look at Exchange 2007’s large new features array. We've discussed the admin goodies and the new Unified Messaging capabilities, but that still leaves out new spam filtering features, compliance reporting features, and more. For those thinking about upgrading to Exchange 2007 from 2003 or even 2000, we suggest heading over to the TechNet knowledge vault and obtaining a trial license as soon as possible. Or hit the TechNet Virtual Labs for some browser-based, hands-on experience. Exchange 2007’s biggest hurdle is its steep learning curve, and most folks need to eat at least part of that before they can effectively plan for an upgrade. Early hands-on evaluation will be key with this one.

Microsoft Office Communications Server 2007 is a breakout communications system for Windows shops, featuring smooth integration of IM, conferencing, and voice telephony. It has great potential to streamline worker interactions within the enterprise, particularly if you're also running Exchange Server 2007 and SharePoint Server 2007 in the server room and Office 2007 on users’ desktops. Its weaknesses are a substantial price and a full-on assumption that the world runs on Windows. Other client platforms aren’t much use with OCS, and even organizations that have already installed a SIP PBX will still need to invest in a media gateway to integrate OCS with the existing phone system and to talk to the outside world.