My company still relies on the antiquated Exchange 2003. Besides using Windows in a virtual machine, has anyone found any type of workaround to enable Exchange 2003 access with OS X apps (Calendar/Address Book/Mail)?
A little amplification of what "apps" you are specifically referring to would be helpful. Assuming your company is using Exchange 2003 SP2, you should be able to use Active Sync with Microsoft Outlook for Mac or Entourage. This should allow you to sync your contacts, email and calendar events. Beyond that an app would need to suport active sync to interact with an Exchange 2003 server natively.
The current Outlook for Mac does not support Exchange 2003 and below, it requires at least Exchange 2007.
Entourage will work if you have a copy of that.
If you don't have Entourage a program like DavMail may be the trick. I was never able to get it working properly with our Exchange server though so mileage may vary.
Personally I ended up using Windows Outlook in Parallels until we upgraded to Exchange 2010. That was the only stable option I could get working... Sorry.