Amigos,
For my personal use and anyone interested check this out:
http://www.ikelite.com/web_two/can_500d.html
TTL circuitry that will work (with Ikelite DS strobes of course) on both the NEW Canon Rebel T1i and Rebel XSi camera.
I recently had a T1i in my hands for a day and think the HD capability is much simpler to initiate and use than the higher priced (although beautiful and more MP, etc.) Canon 5D MK II.
For 99% of users setting the Rebel T1i at 720P (where it runs at 30 FPS) is more than enough to capture some really cool video clips in between shooting 15.1 MP stills......
Plus US pricing is $799.00 USD for a Rebel T1i body!
Technology marches on............
YMMV
dhaas
P.S. - If you already have an Ikelite Rebel XSi housing there is an upgrade program (at very modest cost) to get the extra video control and TTL circuitry upgrade so your housing will work with either camera.