Iophiles should like this one. There are two new papers out.
The first is by Matson et al., which was published online today in the Journal of Geophysical Research-Planets. For those without access to JGR-Planets, this subject has been covered at previous LPSCs. For example, see this abstract and this one.
Rathbun and Spencer have another paper, entitled "Loki, Io: New ground-based observations and a model describing the change from periodic overturn," which is coming out next week in Geophysical Research Letters. For non-GRLers, there's a preprint for this one on the arXiv preprint server.