Is there some advantage to having the SuperUser.apk in /system/app, or would it be equally effective to gain root by running
adb root (restart adbd daemon with root permissions)
adb remount (remount /system partion in read/write mode)
adb push su /system/bin (copy su program to the phone)
adb shell chmod 06755 /system/bin/su (re-secure w/root permission/access)
and then installing the current SuperUser.apk from Android market after reboot?