I had a hard time picking between the Powershot Elph line and the Sony DCS T1 as well. Things that finally made me think about the T1 more was:

larger LCD screen
more pocket friendly form factor
30 fps 640x480 MPEG movie movie mode

The downsides from the Cannon are:
Memory Stick Duo is noticibly more expensive then the Compact Flash or SD cards the Elph line takes.
No USB port on the camera directly. You either need to haul the dock around, or use a media reader if you get the T1.