The matchit.vim script allows you to configure % to match more than just single characters. You can match words and even regular expressions. The default ftplugins include settings for several languages: Ada, ASP with VBS, Csh, DTD, Essbase, Fortran, HTML, JSP (same as HTML), LaTeX, Lua, Pascal, SGML, Shell, Tcsh, Vim, XML. (I no longer keep track, so there may be others.) The documentation (included in the zip file) explains how to configure the script for a new language.
The version for vim 6.x is included in the standard vim distribution, under the macros/ directory; the version here may be more recent.
http://vim.sourceforge.net/scripts/script.php?script_id=39
Comments and Questions
As someone how has been getting along fine for years without this plugin, could you say a little more about why this is useful, perhaps with an example or two? I have my brain wrapped around "% == current file".