I was reviewing a journal paper recently that is closely related to work a colleague and I are doing. We are currently in the process of writing up our paper, and I plan to cite the paper I reviewed in ours. The paper I reviewed has been accepted after two rounds, but has not appeared in print yet. The author does not have a preprint on their website (or other preprint services). We don't build on the reviewed paper I want to cite directly, but our work is closely related. In the future we will probably start building on the reviewed paper, so I want my co-author to be aware of it as soon as possible.
Can I send the last version of the reviewed paper (that I saw) to my colleague? Can I cite the paper as "(in press)" if I submit our paper before the reviewed paper finally appears in print?
Since the paper will appear soon (it's been accepted!) and it is not essential for the present article, why not follow StrongBads' advice, namely submit your article as is, and add the citation in the proofs. Discussing the future with your collaborator can wait a couple of weeks.
Since you sound in a big hurry, I will elaborate in another direction now.
I have always been very adamant about keeping reviewer information confidential. Other people... not: in my discipline (theoretical physics) people have told me that they reviewed my paper or (worse) the paper of somebody else. In short, it is not unheard of to reveal such information, especially when the outcome is acceptance. Is it good for the trade? That's another topic for discussion.
So if you are in a HUGE hurry to discuss with your colleague you may follow Suresh above: if your colleague is not in a different city and you trust each other, you may decide to share the confidential information confidentially, which is to say, just show them the article which you in fact judged positively, discuss it, destroy the evidence. (I've seen that too, and without the destruction-of-the-evidence part.)
Though I personally would just wait...