<p>I have a Nant build script which CruiseControl uses to build a solution on-demand.</p>

<p>However, we only recently got CruiseControl so our official build number is different from what is listed in CruiseControl.</p>

<p>I know CruiseControl injects some properties into build scripts so that I can access the CC build number in the script (CCNetLabel) but how do I pass a value back to CC to use as the build number on the UI screen?</p>

<p>Example, CC says build number 2</p>

<p>nAnt script increments a buildnumber.xml value every build, and the official build number is on 123.</p>

<p>I want the CC UI to show last successful build number: 123, not 2, so how do I pass that value back up?</p>

Did you try to use some environment variables? I believe CCNet can handle these.
I'll dig a bit on this.
Well I see a solution, quite dirty, but anyhow:
1- Add a
defaultlabeller
section in your CCNET project definition. It will contains the pattern of the build number you want to display.
2- Within NAnt, have a script to update your configuration file, inserting the build number you want to see.
3- Touch (in the Unix sense) the ccnet.exe.config file so as to make it re-load the projects configuration files.
et voilà.