I have textures assigned to objects that I'm looking at in my viewport, and I've just updated the texture in photoshop. The texture in the viewport doesn't update until I dig into the material and hit reload (sometimes just looking at the bitmap 'page' will be enough to force a reload though). I had a handy script for maya…
Whats worse though is when it stops redrawing textures at all. Even with a reload and re-pointing to the psd. Those cases, I have to shut down and reopen max. And it usually happens with the same files after 1 or two psd saves... :/ (Max 9 -maybe fixed in later versions. Like I hope the spec dx shader not showing fixed)