There's a Ben 10 MMORPG coming out?

Yup there sure is. Looks to be browser based ... The Examiner reports:

Turnout Ventures today announced an MMORPG based on the popular Cartoon Network cartoon Ben 10.  Ben 10 Omniverse will be a free-to-play, browser-based game with an expected release date of Q4 2009.

Set in the five-year gap between the original Ben 10 series and Ben 10: Alien Force, Ben 10 Omniverse will advance the Ben 10 story through regular content updates.  Characters will be based on skills and DNA rather than classes, allowing for deep character customization.

Ben 10 Omniverse will be suitable for players ages 7 and up.  There is a sign up page for the game's beta here.

(It may be interesting to note that the company producing the game, Turnout Ventures, also has a Tom and Jerry MMORPG in the works!)

For more info: Official Ben 10 website