Of course it's focal length dependent but on Pentax dSLRs with Shake Reduction I regularly manage 1/4 sec with success - it is by no means 100% but most of my shots do come out acceptable at minimum - please see this thread for examples -
Kx in Use
in that thread I also mentioned that I can manage hand-held down to 1 sec - but with my Canon PowerShot G10 compact.
The Canon in lens IS (Image Stabilization) could be better than the in-body sensor SR of Pentax - but the reason for me is the SLR (any) blackout when the shutter is tripped - whereas the Canon p&s has a simple optical viewfinder that I can follow-through keep my eye on the subject during the exposure. This is a very important aspect for longer exposures - and a weakness of any SLR.
Examples -
Pentax K-x
ISO5000, f/3.5, 1/4; 18mm
musicians playing off stage (in the dark)
ISO5000 f/3.5 1/4; 18mm - yes, I was lucky - most of my shots showed SR did its job - but had subject movement .
Canon G10 compact -
last shot may not seem such great shakes (actually operative word)...
but I looked at the EXIF data and realized that is a
1 sec exposure even at ISO800 - yes, I did say handheld
- I had my back leaning against a wall - both hands on camera pressed against my face (hence my mandatory optical viewfinder requirement) - but honestly handheld
- so I would say the IS (Image Stabilization)
does work (and well!).....
EXIF data is attached but PhotoBucket can mysteriously lose metadata.
ISO800, f/2.8, 1.0 sec! 6.1mm (28mm equiv)
Here's the actual pixel crop of that part -
EXIF attached (PhotoBucket caveat)
There is obvious subject movement and also remember the shot is at ISO800 (on the G10 tiny sensor)
where there is quite a bit of softening/lose of detail due to the in-camera noise reduction.
- but one can still see that the stationary objects on stage are without blur.
Just had a thought -
that Canon G10 1sec shot would have been only 1/4 sec on the Pentax K-x
using my normal ISO max of ISO5000, 18mm, f/3.5 would need about 1/4sec for the same exposure
so in that way the Pentax K-x gives equal performance
even if I may not be able to handhold down to 1 sec
(which was/is ridiculous anyway!)