You may be able to take one of the ROMs available in the Rooting/ROMs/Hacks section, open it up, and pull out the Camera application itself. From there it's just a matter of sideloading it. I can't vouch for how feasible this is, but it's the first thing that came to mind. This issue hasn't come up for me before. I'm sure that someone around here can open one up on their desktop and upload it for you quite easily, unfortunately that person isn't me right now.
If you've made a backup of your phone when it had the Camera app on it (via CWM, ROM Manager, Titanium Backup, or similar), you could try using TiBu to restore only the Camera application itself, or by unzipping the backup on your computer and pulling out the Camera app as with a custom ROM. Alternatively, you could do it the other way around: backup your phone via the above methods, restore your phone to a previous backup when you had the Camera app, and then restore the apps/personal data from the backup you make now.
My only disclaimer is that it's four in the morning for me.. I hope the ideas help.