Google recently used Twitter to officially announce the release of the latest update to its ranking algorithm, Panda 3.4. This update rolled out on March 24 andis targeting low-quality websites. The update was specifically a refresh to Panda 3.3, so it seems no new signals or algorithm changes were made. What this means is that Panda 3.4 will have very little impact to the majority of websites.
Google confirmed via Twitter:
Panda refresh rolling out now. Only ~1.6% of queries noticeably affected.
While the 1.6% of websites that were hit will notice quite an impact, this is a very small effect to the overall traffic worldwide.