4870 X2 + 3870 X2 = Crossfire X - will it be possible?

[gcardinal]

Simple quastion:
What holds back 4870 X2 and 3870 X2 to run in Crossfire?

There is repport that it will work and reports that it wont work:
Fudzilla.com
Tomshardware.com

[ExodusC]

CrossfireX currently does not work across series.

However, it always could be possible in the future I guess.

Oh, and that Tom's Hardware article is old and was just speculation. The other article is from Fudzilla, so I won't even comment.