Matt Cutts has provided some more details on the next Google ranking algorithm update to Penguin through the SES event and

We’re still in the early stages of Penguin where the engineers are incorporating new signals and iterating to improve the algorithm. Because of that, expect that the next few Penguin updates will take longer, incorporate additional signals, and as a result will have more noticeable impact.

Certainly links are a primary area to monitor. Been true all this year; expect to continue.

It’s clear that Google is continuing to make real efforts to ‘clean up’ the search results, however with no warning of what is considered “bad” and many accounts of harsh and inconsistent treatments the next few months could be turbulent for many!