I checked late last night and do have 4.09 on my 622. I checked out some MPEG4 national HD and it did look better to me. It seemed detail was a bit improved and the colors more vibrant. I'm not sure how much may have been the material or power of suggestion. They did look better than MPEG2 to my eyes. I can't say I noticed improvement on SD but I have so many channels it's hard to say. Are we talking specific channels or all SD? My opinion at this stage is HD-DVD>MPEG4>MPEG2. If they can continue improving MPEG4 with bitrate and tweaking, this is very encouraging combined with external storage. I don't anticipate them being able to equal HD-DVD but they may be on the way to restoring the HD wow factor.
I'm curious to see what they can do with MPEG4 SD.