<p>The <a href="http://code.google.com/p/v8/wiki/BuildingOnWindows" rel="nofollow noreferrer">build instructions of V8 JavaScript Engine</a> mention only Visual Studio 2005 and 2008. Has anybody been successful with <a href="http://mingw.org/" rel="nofollow noreferrer">MinGW</a> on Windows XP/Vista?</p>

I've tried, but seems it automatically detect the WIN32 platform and tries to invoke the vc++ compiler, I tried to adding to the PATH the mingw-gcc compiler (I've not vc++ installed) and the build script correctly sees it, but doesn't compile out of the box.
I suppose deleting the "WIN32 flag" will do the work, since for successfully compiling under mingw the compiler needs to thinks to be on unix enviroment, but then even if it compiles probably it will have some problems due to the different platform.