Android 1.5 Cupcake Image from TMobile UK.

To upgrade:
Download and copy to your MicroSD card.

1)Turn your phone off. Boot while holding the home button.

2)When you see the triangle, hit Alt+L

3)Then alt+S

4)Press Home and Back when it tells you to (to reboot your phone)

5)You'll notice it says installing Radio after you hit Home+Back (thats normal and fine)

6)You'll see it reboot like 2 times then you'll see the new android loading screen. and there ya go! android 1.5 without having to root/jailbreak and you're good to go. 

7)when 1.5 for the US comes out, just repeat the same process except with the TMobile USA update.zip