You could also experiment with a lower ISO film. The gains that you see are actually physical silver grains in the film that you use. Lower ISO numbers (like ISO 200) have smaller grains.
i had read a while ago, for a digital camera image, to simply give the BLUE channel a slight gaussian blur, it does work slightly, however, at the same point you can create a blue glow if you do too much or lose image sharpness all together.
the despeckle filter works quite well as piner mentioned. i suppose a cross between multiple filters would be an acceptable way to combat this grainyness..
not sure if this helps or not, but i just felt like posting to this discussion :)
'Despeckle' or 'normalize' usually works pretty well, and I'll agree with the low-radius gaussian blur (though I've never tried it on just the blue channel). Afterwards, a 'Sharpen' or 'Unsharp Mask' can bring back most of the detail, but not the grain. I think it takes some experimentation on each individual image, and you can't automatically apply the same thing to all.
I was just working with some prints from books and newspaper for a presentation, and as they are composed of nothing *but* dots, the same technique (larger radius Gaussian Blur and Unsharp Mask) works pretty well to smooth the image and reduce the moire patterns that appear when the program displays at different magnifications.