Pubrank currently is just pagerank based on the citation network. The common way to take time into account is to compute, for example, a "pagerank at 2 years". There are other ways to adjust for time (from linear modeling to more complex approaches) that I'd like to explore.

On average, for reasons that are not clear to me but which emerge from the data, pagerank seems to stabilize around 8 years after publication, for most publications.