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I've got ML DP3 running in Parallels Desktop (7.0.15055). Didin't work in the first time, I had to add 2 cores and 4GB of Ram.
Now downloading DP4 trough the AppStore!
 
I was running the latest Parallels 7 in DP3. When I upgraded to DP4 it opened just fine, no updates or tweaks needed :)
 
The most one would really have to do is just get a patch from Parallels - people have been using it throughout the DP process.
 
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