<p>Is there a way to print out the diffs like they show when you open them with "gvim -d", with all the common code folded away and only the diffs showing in context?  I tried the print menu option, but it printed the entire file that I was currently "in", rather than printing the folded diffs.</p>

I dont think theres a way to get a side by side printout of the two files being diffed. But, you could use Vim's "Convert to HTML" tool on each of the two files being diffed and print those out separately. You could then stack them side by side to get the same effect.
Convert to HTML is kind of "pretty printing" - it saves all of the visual colour/syntax/fold  information.
```
```
:he convert-to-HTML
```
```