Installer fails to run under Mountain Lion with standard settings about git-osx-installer HOT 3 CLOSED

This is not a real issue from this specific application, it applies to all apps 
that do not ship through the app store.
The workaround is easy: just click on the app with while holding the ctrl key 
and choose "open". The same dialog window warning you about the app will 
appear, but with the option to really open the app.

Thanks Daniel for the hint with ctrl -- saved me much hassle for a number of 
apps actually :-)

However, I think you are wrong re: app store shipping. In fact, it is only 
necessary to get an ADC certificate for code signing. While this is really 
mandatory only for MAS distribution, it can also be used to sign installation 
packages, and in fact, Gatekeeper will accept a code-signed app/pkg regardless 
of whether coming through the app store or through a traditional download.

I'd therefore really vote for signing the installer pkg. Shouldn't be too hard 
to come up with 99 quid/yr for the ADC membership -- just make a donation 
account; I (and probably many others) would be happy to help!

-A.