Sysadmin: Free Busy Http Request

http://[exchange server]/public/?cmd=freebusy&start=2009-01-08T07:00:00&end=2009-01-08T17:00:00&interval=30&u=SMTP:[email address]

Output:

<a:response xmlns:a="WM">
<a:recipients>
<a:item>
<a:displayname>All Attendees</a:displayname>
<a:type>1</a:type>
<a:fbdata>00000000000020010030</a:fbdata>
</a:item>
<a:item>
<a:displayname>Joe Blogs</a:displayname>
<a:email type="SMTP">jb@jb.com.au</a:email>
<a:type>1</a:type>
<a:fbdata>00000000000020010030</a:fbdata>
</a:item>
</a:recipients>
</a:response>

Response results are broken into half hour timeslots from 7 AM to 5 PM.
These half hour slots return a single integer.

0 means Free
1 means Tentative
2 means Busy
3 means Out of Office
4 means Unable to find you in exchange dude!