Phil Anderson has a very controversial and thought-provoking article in the latest issue of Science (Science, v.317, p.1705 (2007)). In it, he is questioning whether there really is a bosonic mode that is responsible for the pairing formation in high-Tc superconductors.
The two bosonic modes that are currently in the running as the coupling "glue" are phonons and spin-fluctuations/magnetic modes. These seems to be the more popular consensus that some form of bosonic modes help couple two electrons together to form the Cooper pair. Anderson argues that the evidence for the Hubbard repulsion U>2 eV and that a large antiferromagnetic exchange coupling J~0.12 eV cannot be explained by such bosonic modes. I'm guessing that he is still arguing for his resonance valence band (RVB) model for the cuprate superconductors.
This article should sufficiently annoys a good number of people working in this field. There is seldom a dull moment in the study of high-Tc superconductors, I tell ya!