There’s a big juicy review of senescence in the recent issue of Cell; the article covers a lot of the basic biology of senescence, summarizes very recent findings, and then addresses the ramifications for aging and cancer. From Collado et al.:

Cellular senescence, a state of irreversible growth arrest, can be triggered by multiple mechanisms including telomere shortening, the epigenetic derepression of the INK4a/ARF locus, and DNA damage. Together these mechanisms limit excessive or aberrant cellular proliferation, and so the state of senescence protects against the development of cancer. Recent evidence suggests that cellular senescence also may be involved in aging.

This is one of those “everything in one place” types of reviews, and I consider it essential reading for those entering the field as well as those of us who are already elbow-deep in it.