Yes, the sensor noise is an interesting one. I've recently got my first results at 3200 ISO:
http://www.nightfolio.co.uk/subpages/as013.html
The Live View focusing is wonderful:
http://www.nightfolio.co.uk/tokina/lens_test.html
I'm having trouble getting hold of a Canon cable release for the 40D here in the UK, I've ordered one from the US, I'm praying it will arrive before this week's full moon. Until it comes I am limited to 30 seconds exposure!