There are lots of great platformers on PSN. In terms of retail games, some of the disney releases, while aimed at the younger end of the market are pretty good platform adventures (i played cloudy with a chance of meatballs to the end, and enjoyed it). i've said it before, and i'll say it again inFamous is a truly brilliant game. loved, loved, loved it. Then theres plenty outside of your comfort zone that are great and can be picked up relatively cheap: wipeout fury, singstar (great with a buch of drunk friends), motorstorm, pain, buzz.
if you don't have already on 360, then the need for speed games, burnout paradise, skate franchise, lego games, virua tennis, fifa. All worth a play imho.
If it's strictly cutesy platformers you are after, and the ones on PSN don't float your boat, then i'd save your cash and hold out for nintendo's next console.