The New Way

There's a (currently undocumented feature) that allows you to override the current page's title:

_gaq.push([_set, title, Your Brand New Page Title]);

_gaq.push([_trackPageview]); //will send with the overridden page title

The Old Way

Google Analytics gets the title information from document.title, so you could just set document.title before Google Analytics runs to whatever value you want it to be.

_gaq.push(function(){

    var oldtitle = document.title; 

    document.title = More Descriptive Title;

    _gaq.push([_trackPageview]);

    document.title = oldtitle;

});

Tests in Chrome seem to indicate that this doesn't cause a title flicker, but your results may vary.