Well, this looks to be a little different from my prediction (A700 with a new nametag), but some of my guesses seem to have been right.
12.3MP CMOS - I assume this is either the A700 or D90 sensor. Either way I'm happy, as from what I've seen they both have rather good high ISO performance, at least compared to my A200
Main Sensor LV - very pleased about this. Not sure how much I'd use it, but I can see it being very useful for macro, which I do occasionally.
5fps - as well as being very useful, this could signify that this camera is seen as more like the A700 than the 200/300/350, If you see what I mean. Another thing that would aid this distinction would be if the 500 has a pentaprism OVF, but the site makes no mention of the VF. Here's hoping.
SD/MS slot - while I suppose this is a positive to a certain extent, I just wish it could've been CF/SD - that way, I can keep my current CF card, and make use of the cheaper price of SD cards. Looking at MS prices, I am decided that there's no way in hell of me wasting money on any form of MS memory - it's ludicrously overpriced. However, if I do buy this camera, I can always buy an SD and keep my CF for a future upgrade, or use it in my A200 as a backup, or something.
230k dot LCD - not a huge deal, but apparently the A700's screen was really awesome, so it's a shame that it's got a lower res one.
9-point AF - this is kind of annoying. Apparently the A700's AF is a lot better than the 200/300/350, so this is a little annoying, though it does mention that it has a central double-cross sensor, and AFAIK the 200/300/350 just have a normal cross sensor, so there might be hope yet. Though, if this is a whole new AF module, does that mean that the 730 or whatever will share it? I sure hope not - I'm hoping for a 20+ point system for that camera, with lots of cross and doublecross sensors. Or dos the 230/330/380 use this same AF module?
Viewfinder - this is fairly important. Ideally it would be pentaprism, and fairly big compared to my A200 (not necessarily that much bigger, but not smaller). What I definately don't want to see is a 3-series size viewfinder. I knew these were smaller than the A200's for quite a while, but it wasn't until I tried out an A330 in a shop that I discovered just how tiny it is - like peering down a tunnel. So, I really hope Sony have managed to keep the OVF as big as the A700 or at least A200 while adding fast AF LV.
Controls - we don't have any images of the rear of the camera, so we don't know what kind of controls this camera has. I'm personally hoping for A700-style, with lots of buttons, switches, knobs etc.
Video - The article doesn't mention video at all as far as i can see, which we can probably take to mean it's not there. However, they're getting their info from a "source", so they haven't actually tried it out yet, so it might turn out to have video after all. I would be quite interested in video for the purposes of filming wildlife - short clips of them doing some kind of action, along with still clips, could be very interesting. There's also always the possibility that the 550 will have video, where the 500 doesn't. We'll have to see.
A550 - as I said above, one possibility for the 550 is that it while include video, where the 500 lacks it. However, if the 300/350 pattern is to continue, then it's more likely that they will be seperated by resolution - my guess would be for the 550 to use a new 14-16MP CMOS sensor, which the A700 will share when it's eventually released (my guess is early 2010, either before or during PMA)
Overall, I'm pretty pleased with the A500. The price looks great (roughly the same as what the A700 sells for now, after two years). It might not be everything I hoped (though the viewfinder and video capabilities remain to be seen), but it's still a solid camera.
Nice move, Sony