<p>I've seen a few examples on how to do build deployment, however I have something unique that I'd like to do:</p>

<ol>
<li>Deploy the build to a folder that has the build number (eg. Project\Builds\8423)</li>
<li>Alter the version number in the .NET AssmblyInfo.cs to match the build number</li>
</ol>

<p>Has anyone done this before with .NET projects using NAnt + CruiseControl.net?</p>

i haven't done it with nant, but we have written a custom application in C# that reads the  assembly and increments the release number.
we call it from an exec block in the ccnet config.
creating a folder and copying files would be trivial to add to that application
our thinking was we use C# all day, so it would be quicker to fix/alter the build program written in C#, then if we had to learn the intracies of nant scripts on top of that
obviously if you use nant all the time, there would be no reason not to build a custom nant plugin to do the job