you found it at /download/OTA Update file.zip/firmware.zip , correct? cause thats where i found it, and would explain why i couldnt find it simply using ASTRO on the phone.EDIT: I'm not sure I made everything clear.
1. Make sure you've downloaded the OTA update (though you haven't installed it yet).
2. Mount your device as a USB drive.
3. In that USB drive look in the download directory.
4. There'll be a .zip file of almost 300MB in size. That will probably be the Gingerbread OTA ROM update.
5. From that .zip file you should be able to find something called recovery.img.
Not sure what else needs to be clarified.
On a different note, would you say updating was worth losing root? Thats the only thing holding me back so far.