According to W3Techs, Ubuntu is the only web server OS showing a continuous growth rate for (at least) the last year. After passing Suse and Fedora last year, we passed in front of RHEL usage in July. CentOS and Debian are still ahead though.

Stephen O'Grady (RedMonk) recently published on SlideShare a sample of his report on the "State of Novell". Of course, I had a twisted look at it with an Ubuntu perspective, and while some of the data was already known to me, a few elements caught my attention.
First of all, the job trend graph from indeed.com shows that job offers with some sort of Ubuntu skill are steadily growing:
(revision 18/03/11: using an updated graph showing debian as well as suggested by jef in comments)
The 2010 Eclipse community survey [PDF] has just been released, and again Linux and Ubuntu is showing strong growth on the developer workstations. Some of you may remember my post on this subject last year.
From last year Windows continued its decline, while Linux continued its ascent as a developer platform:

Working from the ODS document that provides additional data, I then dug up the linux OS stats. Ubuntu has grown from 14.4% last year to 18.3% this year, or 56.1% of those running Linux as their development platform.
Gerry Carr, Canonical's head of platform marketing, announced today the availability of the results for the second Ubuntu Server Edition Survey. With almost 3000 respondants, this survey allows us to get a feeling of how the server users of Ubuntu are working with our product, and the learnings are always quite interesting.
On Monday our partner Groundwork Open Source, whom are selling a monitoring solutions that they recently certified for Ubuntu, published their statistics of the OS on which they see GWOS running on.
According to the statistics page on the Cloud Market, which claims to be "the most complete catalog of Amazon EC2 images", images using Ubuntu as the base platform have the largest share in their catalog.
Some people may say that I am a statistics junky... Well that's certainly true! But what do you want, being a product manager for a product that does not require ANY form of user registration, you have a tendancy to cling to any piece of data you may find that shows that you are not working in vain. Indeed, and to the opposite of most, if not all, of our competitors, we have absolutely no way to determine what is our install base. We don't control our mirors, we don't have any ping back home mechanisms, and we are not considering adding any. So, here I am, collecting as much information I can from outside sources...
Well, october was not too bad in that sense:
A few minutes ago my colleague Simon Wardley asked me a simple question: do we have any graphs that shows the adoption of Ubuntu Server Edition over time, other than Google trend? I could not think of any, so I figured to produce one out of the results from the Alfresco Open Source Barometer since they have now released their results three times. Here it is:

The Eclipse Foundation just released its 2009 Community Survey , and this brings some very good news for Linux and Ubuntu.
Great news for Linux, as it has clearly gained ground very fast both as a development and as a deployment platform since 2007. Ars Technica covers the details, but here is the graph they have produced of this growth:
Looking into the details of the survey, Ubuntu is clearly the second OS for Development (14,4%) behind Windows (63,9%) and more than twice the share of MacOSX (6,9%) :
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