What changed in merge commit?

Since today seems to be my day to hang out on this list, I thought I'd ask another burning question...

How can I see what changed in a merge commit?

$ git log

just says "merge remote branch 'origin/master' into wpd" and

$ git log --name-status

says the same thing -- it doesn't list any files as having changed.

Perhaps nothing changed between the last time I merged with origin/master and the current time. I know that at least one change was committed. I suppose it's possible that two (or more) changes were committed, undoing that one change. (But I don't think that's likely).

I could go back and look at the log for origin/master... and I'm sure there's some way to say "just give me the log of changes since the last time I merged", or more to the point now, "just give me the log of changes since the time before the last time I merged". It probably has something to do with a couple of ref names, a caret, and some dots, but I get lost in all of that syntax.

Thanks for the tips.

--wpd