Recently there has been a lot of conversation on the public mailing lists about COLLADA and X3D. As is usual with standards discussions, there is an attempt to create a "which is better" division - kind of a World Wrestling Entertainment Smackdown between COLLADA and X3D. But I think that spectacle is artificially contrived and created in part by confusion about what goals and markets X3D and COLLADA actually target....
Open Standards for Real-Time 3D Communication
A nonprofit organization that develops and maintains the X3D standard--a 3D file format and runtime specification that is open, royalty free and ISO ratified for transmission of 3D data over networks.