On January 23rd, 2017 Oracle published a new version of their “Licensing Oracle Software in the Cloud Computing Environment” document.
The current version is available here: http://www.oracle.com/us/corporate/pricing/cloud-licensing-070579.pdf
Previously, a virtual database server with 8 virtual cores running Oracle Enterprise Edition in an authorized cloud environment needed 8* 0.5 =4 processor licenses.
Now, the same server on MS Azure (all instance types) or on AWS servers that do NOT have hyperthreading (namely the t2 and m3.medium instance types as stated here: https://aws.amazon.com/ec2/instance-types/) will need 8 processor licenses.
For Standard Edition licenses, the document makes no difference regarding hyper-threading and simply sets back MS Azure users: One processor license is needed for four or fewer AWS vCPUs, however one processor license is needed for just two or fewer
AWS (correction) Azure vCPUs.
Additionally, Oracle halved the maximum number of vCPUs that you are allowed to use in Azure instances running Standard Edition 2 from eight to four.
In other news: I have added a piece of paper to my copy of my employment contract stating that, in effect as of today, my hour no longer has 60, but only 30 minutes.
Edit: Tim Hall’s take on this: https://oracle-base.com/blog/2017/01/28/oracles-cloud-licensing-change-be-warned/