Yes with OS 5.0 you can use Themes as long as they are the same resolution, 480x360. This means you should be able to download and use any Theme for the 8900 or 9630.
Posted from my CrackBerry at wapforums.crackberry.com
Just a heads up. I used a 8900 theme and ended up nuking the phone. It initially took a really long time to restart. Then one day the data arrows got stuck showing on the top right corner of the screen. After I did a battery pull it wouldn't complete the restart. It would just turn back off and restart all over again. When I was reading the how to fix a nuked berry 101, it said that themes not meant for the phone can be the cause, and I wasn't having any problems with it until I installed a theme. So lesson learned, I'm just gonna wait for a 9700 version of the theme I want
Posted from my CrackBerry at wapforums.crackberry.com
Check out this theme http://forums.crackberry.com/f129/fr...8900-a-349923/
It's an 8900 theme that was modded for the 9700, looks and works great. I've been missing some of my 9000's theme's but this one helped me get over it, good looking theme.