After a reinstallation of WSUS on a ConfigMgr 2007 server the MP was not working anymore.

I looked in the mpcontrol.log and should see that the MP was not working. I could see no "Call to HttpSendRequestSync succeeded for port 80 with status code 200, text: OK" lines. Those lines will be there if the MP is working as it should.
I could see in the mpsetup.log that it was trying to install the MP again and again but it kept failing.

In the MPMSI.logfile I found the following line:
“Product: SMS Management Point -- Error 25006. Setup was unable to create the Internet virtual directory CCM_Incoming”

After googling the problem I found the solution here.
The Bits service had to be reinstalled. After doing that the MP installed successfully

Last friday Microsoft released System Center 2012 Service Pack 1 Community Technology Preview (CTP2).

Included in the CTP2 is CTP2 SP1 for ConfigMgr 2012 that Kent Agerlund described here.

You can download the CTP2 here.