Clearly, at this point anyway, the other Dems don't see Clark as the front-runner, but rather still see Dean as the occupier of that slot:

Retired Army Gen. Wesley K. Clark was the object of curiosity, while former Vermont governor Howard Dean was the target for attack.

[...]

In contrast to Clark, Dean was very much at the center of the action throughout the debate, most of the time on the defensive.

That is to say that if the other Nine felt more threatened by Clark, there would have been more attacks--the opportunity was certainly there. As it is, they clearly consider Dean the main threat (as the poll numbers from NH show) and are going to wait and see on Clark. I still think a lot of them are thinking he would be a great running mate, and so will probably not attack unless he becomes a bigger threat to their positions.

Source: Among the 10, Two Are Tested the Most