There are a couple ways to add autodiscover - which is required by Exchange 2007 (and presumably Exchange 2010) for full functionality (more coming on this concept).
One method is to add an SRV record. Because nothing is easy, not all DNS editors allow you to create SRV records. Sometimes, you can add them yourself. Sometimes, you have to write to support. Sometimes, it can't be done. But when it is done, here is how to check on it:
In a DOS prompt, type "nslookup"
Then "set type=srv"
Then the record you want - such as "_autodiscover._tcp.exampledomain.com"
Here's what a properly configured autodiscover looks like: