The trick is to have the ShowTaskbarIcon=0 line in the [VRDB] section of the file. This will disable only the VRDB icon, not the main icon.
No, that's not the trick. I just tried it, and it removed the main icon instead, and the VRDB icon shows up when it's generating the VRDB. Anyone got a solution for this yet? I'm getting really annoyed with the VRDB icon. Will this be fixed in the next version, so the "Merge with main avast! icon" option actually works?