There’s been some talk about possible data refresh or algo update at Google as there has been a fair amount of ranking fluctuation over the past few days.

Matt Cutts has answered the question by denying any algo update. However, he did explain the differences between an algorithm update, data refresh and index update –

Algorithm update: Typically yields changes in the search results on the larger end of the spectrum. Algorithms can change at any time, but noticeable changes tend to be less frequent.

Data refresh: When data is refreshed within an existing algorithm. Changes are typically toward the less-impactful end of the spectrum, and are often so small that people don’t even notice. One of the smallest types of data refreshes is an:

Index update: When new indexing data is pushed out to data centers. From the summer of 2000 to the summer of 2003, index updates tended to happen about once a month. The resulting changes were called the Google Dance. The Google Dance occurred over the course of 6-8 days because each data center in turn had to be taken out of rotation and loaded with an entirely new web index, and that took time. In the summer of 2003 (the Google Dance called “Update Fritz”), Google switched to an index that was incrementally updated every day (or faster). Instead of a monolithic monthly event, the Google would refresh some of its index pretty much every day, which generated much smaller day-to-day changes that some people called everflux. Over the years, Google’s indexing has been streamlined, to the point where most regular people don’t even notice the index updating. As a result, the terms “everflux,” “Google Dance,” and “index update” are hardly ever used anymore (or they’re used incorrectly :) ). Instead, most SEOs talk about algorithm updates or data updates/refreshes. Most data refreshes are index updates, although occasionally a data refresh will happen outside of the day-to-day index updates. For example, updated backlinks and PageRanks are made visible every 3-4 months.

This pretty much suggests any movement we are currently seeing is a data refresh of somekind.