no thats a blow off valve. a wastegate regulates the speed of which the turbo spins, the faster it spins the more air it pushes and the more boost pressure it creates. the wastegate sits in between the exaust manifold and the turbo. the exhaust gas is what spins the turbo, so basically when the turbo hits its desired speed(or the amount or boost pressure its creating) the wasegate will open a certain amount(determined by the spring or boost controller) to vent out the excess exhaust gas that would spin the turbo faster and create too much boost.

why some people dont like the deltagate is because the valve where it dispenses exhaust gas is a lot smaller than the tial. so what happens is there too much exhaust gas produced under high boost and the wastegate cant vent it all out thru this small valve, thus creating 'boost creep', which is when the boost goes above the desired wastegate level.

hope that helps