I am the lead developer of a application called Leonardo that we hope will be a future "Photoshop killer" when it comes to digital painting: http://www.getleonardo.com The main focus for us is speed and Leonardo is way faster then any other application including Photoshop (and it is still raster based).
Leonardo is not finished yet, but it is possible to sign up on out beta list.
Leonardo is not finished yet, but it is possible to sign up on out beta list.