If you are hooked up to WIFI on both phones, install File Share from the market on the host phone and add the file to Shared Folders. Then, log onto the URL listed at the bottom of File Share on the second phone and click on PUBLIC. You'll see your shared file and can then download it to the other phone.
I've also used Blue Tooth Transfer between phones but sometimes have issues downloading. When this happens, I just go to the other phone and upload. I think File Share is more user friendly.