I want to do the same thing chameeeleon and decksnap are trying to do.
Previously, I used MS Photo Editor under WinXP to edit and rename my photos.
I would love to use iPhoto 5 on my new Mac mini to finally manage correctly all of the photos I have. The lack of being able to rename the actual file is very limiting.
Why? Because when I share photos with others or take them to a local place to have prints made of them, the criptic filename my digital camera gives the picture can be very confusing.
The title in iPhoto is nice, but it's pretty useless when it comes to copying that JPG file to another computer and knowing what the picture is.
IMG00DHJFH.JPG = useless
family-picnic-park-01-050105.JPG = more descriptive
In my google searches, I've found a few renaming utilities, but so far, none of them (at least for the Mac) show the picture while you are renaming it (helpful for reducing the amount of close/reopen steps you need to rename the actual file of the photo).
For now, my work-around is to open each file in Preview and then close the file and rename it. It's not pretty by any means, but it works.
I've been tempted to load Picasa 2 under my VPC 7 WinXP, but that requires moving the pictures to the VPC then moving them back.