Seriously, it is. And while it may not necessary be an attack on Wikipedia, it sure does seem that way. At least to most people.
For those not in the know, Knol is Google's lastest project, aimed at having users write articles on whatever they choose to for the benefit of others. So long as you have an account, you can join in and write (hopefully) about what you know. One thing I've noticed is the use of people's actual names for those who publish articles. I don't recall ever really noticing that on wikipedia.
Another thing is the lack of pictures. I don't see much pictures and diagrams on Knol. Look at these two pages on entrepreneurship - one from Wikipedia and the other from Knol. Wikipedia has two related diagrams on their page while Knol doesn't. Finally, Wikipedia has a lot of links to related articles within the wikisphere. Knol doesn't point inward of itself to refer people to new ideas within the text of any given article.
I must say that for now, I'm going to stick with Wikipedia, mainly because it has a larger base of knowledge (it appears that Knol has about seven pages worth of "featured" articles). But, I'm sure that as time goes on, Knol will grow to be a much more realistic alternative to the Wiki-King.