Yup - its stuff like hyaluronic acid or collagen injected into your cheeks, brows etc.. (e.g. restylane)
Its a temp non-surgical method of plumping up your face/lips..
I'd like to know because apparently more aging than wrinkles is the the loss of volume from your face, and I think I am starting to lose some of that plumpness from my mine!
I believe there is no downtime at all and results are seen immeadiately. I've heard positive reviews, but I'd recommend checking out the RealSelf reviews for each different type of filler. (For example, here is the page for Radiesse). This doctor's dermal filler page lists more fillers.