Looks like most of us have moved far away from answering the original question about whether there is any value in linking to PR0.

So here's the PR equation when it was first released:

PR(A) = (1-d) + d(PR(t1)/C(t1) + ... + PR(tn)/C(tn))

It is generally believed that d=0.85

So what the equation tells us is

PR = 1 - 0.85 + (contribution from backlinks) = 0.15 + (contribution from backlinks)

A PR0 page would then have at least 0.15 to give to pages that it links to. So it's still worthwhile to get a link from a PR0. The contribution to your pagerank may be small, but it is positive.