An Android 2.3.6 Gingerbread update was available for the AT&T Samsung Infuse 4G at the beginning of the month but it looks like you won’t be getting it in the next couple of days if you missed out on it.
According to Samsung the update is currently on hold. The manufacturer and the carrier “are aware there is an issue with the Infuse 4G update that affects a small number of users”. When will it go live? Whenever the fix, currently in development, will be ready. Our advice to you is to refrain from updating your device with the previous refresh even if you manage to find it somewhere else. It shouldn’t take long (hopefully) for the process to resume.