Sorry I started a new topic (I did make 3 posts in the other one), I figured many people wouldn't have seen it if it was posted in a rumor topic, so I made it official.
Most of the size difference is in width, PS2 model 1 being over 3 inches (w) and the new model being 1 inch (w). It is smaller all around but it's length keeps it from being walkman type pocket size.
I don't see that it is a top loader, but nor do I see that it is a front loader. I'd like a front loader but if it's top loading that will mean no more disc read errors (from the bad gear mechanism that caused 95% of them). The two usb slots are right next to the controller slots.
As far as HD support, I don't think Sony ever had a plan to do much with it for PS2. Seeing that FFXI was going to utilize it though they came out with it, and including FFXI bundled furthers the fact that they may have released it to avoid having to deal with a bad situation with SquareEnix (SNES CD...). Although there is also the fact that the people who buy a PS2 now, are mostly people with less money and casual gamers, the old adaptors who won't be inclined to buy the HD for a limited # of games for it. So they will be displeasing a very small # of people, and there is the chance that they could release something to allow HD access or even a better HD model (not PS2 HD model, just a new HD).
As far as the door release I don't think it's where the memory cards are because there is an eject button to the right of the controller and memory card slots. Looking at it closely, it does look like a front loader.