Have a thought on this Market issue but I can't mess with it atm as I'm at the office and don't have the info handy.
anywhoo if you guys have a copy of the ED2 software take a look at the build.prop and look for the finger print line. Copy that down and then edit the build.prop in the newest GC build to match it. Once done reboot the device and see if the app will download correctly. If that fixes it plz post the fingerprint info from the ED2 build so other can can test this
Edit: Okay just got home folks and tried my suggestion out. That said the app being discussed not showing up DOES show up in the Market now and installs correctly after editing the build.prop file. So everyone knows if they want to edit it here is the info that needs to be changed so it works right. Just edit these 2 lines in your current build.prop to show like I will post below. Once done save the changes and reboot the device. BTW I did this via Root Explorer. You can do it via ADB also but you will have to pull the build.prop make the edits and then push it back.
ro.build.description=SCH-I510-user 2.2.1 FROYO ED2 release-keys
ro.build.fingerprint=verizon/SCH-I510/SCH-I510/SCH-I510:2.2.1/FROYO/ED2:user/release-keys