How can I justify my lack of publications?

I have only 2 publications from my PhD, and I am applying for a post-doc position.

I am already a postdoc and I am finishing 2 publications, and my collaborators are going to write other 2. The problems are: I have no idea when those 2 papers, that I am going to be co-author, will be published; the only proof I have publications is those 2 from my PhD, which are not really connected with the position I am applying for.

How to justify then my lack of publications in my application form? I always had this felling that put in my publication list, "manuscript in preparation" sounds weird, even if it is the true.