I've been using a couple of HDR programs for a while now, and decided to go back to Photoshop's Merge to HDR to see if my new skills make Photoshop's HDR work better for me than it had in the past.
I had tried it when I used CS3, and confess that I didn't really understand the various choices. No longer haveing CS3 on the computer, I fired up CS4 and much to my surprise the only choice available in the Merge To HDR dialog concerned preset curves. Gone were the choices of tone-mapping paradigms, and the resulting image was processed entirely automatically.
Did Adobe remove the HDR options from CS4 and make them available only in the CS4 extended version? I really resent Adobe's splitting of the features, following the path of Microsoft with the multiple versions of each OS.