>>31
It's not theory but has been done since the beginning of PSX emulation.
It looks kind of like this:
http://www.vince.emuxhaven.net/images/ePSXeSetup/PsGame.jpg
It doesn't do wonders but it looks much better than rendering at 320x230 and then scaling it up in any case. But I agree that using filters looks like crap most of the time. However, there are exceptions, especially games that have large areas with he same color and not too much detail where using something like hq4x will yield great results. Yoshi's Story is a prime example of this.