Rosie, the stock launcher that comes with Sense, has a problem. It was designed for a smaller screen, and even though we have significantly better hardware and more landscape to play with these days, it's still set up for a phone with half an inch less of screen room.
Well, now there's a mod that will take you from four icons wide by four high to four wide by five high, allowing an extra 4 icons to be displayed per screen and not look at all out of place.
There are no options; you simply flash the zip and that's that. If you want to revert back to stock, as far as I can tell you'll have to restore a Nandroid or install a new ROM, so make sure to make one before you flash.
A quick note for the widget fans out there: just because you can fit four more widgets on a screen doesn't mean you have to. The more widgets you have displayed, the more the phone has to work when redrawing the screen or updating what's visible.