I have a set of vector icons which I need to save as PNG images in 3 sizes (16,32,48). I'm confused as the best way to go about this to produce the best quality results. Either I can save each one individually at each size from within illustrator or I produce the largest size from illustrator (48x48) and then simply resize them down using my handy batch image resizing tool. Is there a difference in the quality the would be produced between these two methods?
It depends somewhat on the icons. Unless the job is paying by the hour, I'd definitely try the batch method first, because the quality difference is likely to be so slight as to be no difference at all.
If you have Photoshop CS5 or 5.1, you could run Image Processor Pro and save all three versions at once, with a separate subfolder for each size.
If not, an Illustrator action that saves each size for a given image would certainly speed things up for you.