SatanicFreak recently released a Tetris game for GBA. You can get the download from his page. Thanks to GBAdev.org for the news.

Author release notes:

01/02/03 Fixed BlocksI fixed the game and uploaded it again. The previous version I had on the website had some glitches that needed to be worked on.12/31/02 Finished BlocksI just got done with my tetris clone on the gba, it still doesnt have sound but thats alright. I am going to move on and make other games. I also uploaded the source, feel free to use it as long as you give me some credit.

http://www.geocities.com/supersatanicfreak/news.html