I just committed a new version of Quick Open to the repository, see http://lists.macromates.com/pipermail/textmate-dev/2007-April/ 008810.html for the commit message.
I hope this version is satisfactory, it will by default run gcc/g++ (which is fast enough), but you can set the search path manually if this is not desired -- I split the variable into a user and system search path.
I am thinking this script should also be the basis of the include/ import completion.