Exactly what I needed! Long-time user of (first) Glims and (later) SafariStand, and for the most part I used the latter to add favicons to the tabs. SafariStand injection is no more, short of patching /Applications/Safari.app itself, so until Apple adds favicons (which might never happen, because it can look really ugly, depending on the favicon), this is the best thing you can have. Sure, it's just an overlay, so there's a slight lag, when adding a new tab, rearranging tabs etc., but it's not possible to do it any differently. (I believe a very similar method is used by Default Folder X now.)
As for the the functionality itself, one idea for enhancement: if favicons (like the MU of MacUpdate) have transparency, the "x" of the tab-close button will shine through, when the user moves the pointer over the tab (highlight tab), so Faviconographer should maybe put an image layer beneath the favicon layer that has the same grey tone/tint/hue as the tab beneath it. (Or do something else completely, like fading out the favicon completely, if the user hovers over the tab with the mouse pointer.)