OK, so what are the drawbacks to using the POTY2003 in 2006? I will address the three main flaws and try to present a case for sticking with the T610 for now.
1. The built-in memory is pathetic. This is true. But a way to stretch that memory a little further is to delete all extras that you never use: games (I never played them, so I deleted all of them) and pre-installed wallpaper and images (who needs them?) can go.
2. The built-in camera is pathetic. Yep. But! With a nice tiny digital camera like the T-33 or the Optio S6 in your pocket, who cares? Instead of taking bad pictures on your T610, shoot nice ones with your real camera and put them on your Mac. Then crop them to the same size as the T610 screen, use the Save For Web option in Photoshop, and then Bluetooth them over to the phone. Your pictures will usually be a third to half the size of a photo shot with the built-in camera, and the resolution and quality will be much higher. So, save space and get nicer looking pictures. The T610 can display great color and is very bright, but you'd never know it based on the photos taken by the phone.
3. It doesn't play mp3s. Nothing is going to change this, but as an iPod user, I can't say that it bothers me too much. I like the idea of the W800 and I would be open to it if I didn't already have an mp3 player. A good companion to the T610 in 2006 might be the iPod nano, but that's material for another post.
In somma: the T610 is a workhorse and my battery still holds a great charge almost two years later. The design is elegant and SE have yet to sell something that looks better in the same form factor, W800 included. If a new, better SE phone can be had for free (or if Amazon wants to pay you to take it) then there is no sense in clinging to the T610. But for someone without a US-based cell plan, it still makes sense. It still looks great when you set it on your table at a bar (as everyone seems to do immediately in Italy). The T610 has its limitations, but none that make it unusasble in 2006.