Just hours ago, a SpongeBob SquarePants casual MMO was confirmed and it will be published in 2011. It will be a joint venture between MTV Networks Asia and GigaMedia, a developer headquartered in Hong Kong with offices around Asia. While not much is known of the game, its confirmed to be a Free to Play title with a cash shop. There will also be exclusive content restricted to the MMO not found in the cartoon, including an expanded area of Bikini Bottom.
I am not really sure if this will be a client-based MMO or a browser-based MMO, but the game is said to have Flash games catered to players of different ages, so it will most probably be a browser-based MMO. Confirmed regions of the game include China, Japan, Korea, Taiwan, South East Asia (SEA) and India. More official news will be revealed in 2011.