UPD! This way it not works at all.
Today i've tested:

Camera 360
Camera 3D
Camera Advance
Camera Pro
CameraX
Camera ZOOM FX
eCamera
Fast Burst Camera
LG camera
MIUI Camera Beta
Pro hdr camera
PRO Paint Camera / PRO Zoom Camera 5X
Pudding Camera
Snap Photo Pro

Noone works proper good.

Here is the FROYO 2.2 Original camera *.apk
Since this is a system app, it cannot be installed using the Package Installer. Camera.apk must replace /system/app/Camera.apk.
You can use ADB to push it ("adb push Camera.apk /system/app/Camera.apk"); or copy Camera.apk to your SD card, then use a program like Root Explorer to move it to "/system/app/"

UPD! F*CK. And this way is also doesn't work - update with new camera just don't switch it.