[Oblivion Knight]

I also had the problem with group thumbnails showing fullsize, so I decided to use custom statusicons per groupid with this little edit of your forumhome_start plugin:

if ($vbulletin->options['cel_sgfh_iconfile'])
{
	$oldicon = "group" . $cel_groups[groupid] . "_old";
	$newicon = "group" . $cel_groups[groupid] . "_new";
}

Then for each group, you need to upload groupX_old.gif and groupX_new.gif to images/statusicon, replacing X with the groupid.

Of course, this is only particularly useful if only admins can create social groups. It's not much good if you allow members to create their own, and/or if you have LOADS of them.