Konami is apparently working on a new 2D Castlevania game, similar to the PSX's Symphony of the Night, and GBA's Circle of the Moon.
Previously there were rumors on not only a new Castlevania game on PS2, but another on the Game Boy Advance, again in the action RPG vein of Circle of the Moon.
Though nothing is really official still, it seems Konami is sticking with 2D for the series now, after the failed 3D outings on the Nintendo 64. And that's always a good thing.
Stay tuned to RPGFan for more news regarding both supposed titles.