Google should wake up and announce Google Exchange: the Google alternative to Microsoft Exchange. However, the good news is that you don't need to wait for Google product management to figure out the obvious and make the official announcement--you can start investigating it today.
To be truthful, I'm not convinced it's fully baked yet. In the updated version of my Google Apps report (released today), I say, "GAPE is on the road to becoming a credible replacement for Microsoft Exchange if an enterprise wants to stop paying for Exchange server and CALs licenses but wants to keep Microsoft Office." Notice that I don't say "is a credible replacement," but instead say "on the road to becoming a credible replacement." However, at this point I think some enterprises may be willing to accept some product deficits to gain savings.
I didn't say this back in August 2007 when the first version of the Google Apps report came out, so what's changed?
- IMAP Support: Google Apps now supports IMAP. This means that Microsoft Outlook can store Gmail messages offline.
- Google Calendar/Microsoft Outlook Sync: Google Calendar can now synchronize with the Microsoft Outlook calendar.
- Better Exchange Documentation from Microsoft: Today, Microsoft posted detailed information on how Microsoft Exchange Server 2007 and Microsoft Outlook talk between themselves on MSDN. In other words, with this free documentation, it's going to be easier for Google and others to replicate Exchange/Outlook behavior.
- New Add-Ons: Today, Cemaphore Systems announced MailShadow for Google Apps (currently in beta), an application that will synchronize Outlook e-mail, calendar, and contacts with Gmail.
Product deficits? You can't yet have proxy users in Gmail--for example, a secretary logging in to manage the e-mail and calendar of his or her boss--but I suspect Google is working on that. I'd also look into how recurring appointments are handled.
However, given how the costs of Exchange can add up (hardware, Exchange Server license(s), Client Access Licenses, and trained staff to manage it all), using Google Apps to cut e-mail costs can be attractive to enterprises looking to cut IT costs without disrupting their users' Office world. And while Microsoft offers Hosted Exchange, from what clients have told me you end up paying Microsoft more for less e-mail storage.
Finally, this is really how Google Apps is being used in many large organizations (read "large universities"). Universities always roll out the Gmail portion of the solution, but sometimes get resistance on the apps part (Docs, Spreadsheets, Presentations) since they're less functional than their Microsoft Office counterparts. While I hear complaints about the apps, Gmail is almost never mentioned. And if it is, it's the user interface portion. Using Gmail as the backend to Microsoft Outlook fixes that problem.
So rather than thinking about Google Apps as a combo Office/SharePoint/collaboration wannabe, adjust your viewpoint and think of it as an e-mail server. With that in mind, Google Apps may make sense for your enterprise.