Wendy,
Its to reduce the distance between nose and lip.
From your avator photo Melissa, I don't think you need it.
Though I admit the photo is not the highest quality.
Also, often when they lift the lip, they also unroll it somewhat which makes it appear bigger (it shows more of the red part). So, it has a double utility.
Seeing as to the possibility of scaring, I'd be afraid myself to do it.
Though My lip already lets 3-4 mm of teeth show so I would look like a
beaver if they pulled the lips higher ;-). If I eventually do it, I'd try
lip suspension. Its a new fully reversible method that leaves no scars, which is good when you only need a minor lift.