I've generated the first Sakai 2.6.0 tag for QA: sakai-2.6.0-alpha01. It is available at
https://source.sakaiproject.org/svn/sakai/tags/sakai-2.6.0-alpha01
I originally planned on creating a 2.6.0 branch (in line with what I do for maintenance releases) and then cutting the alpha01 tag from it once I had tweeked the POM values to more closely match the tag name but my colleagues prevailed on me to hold off on branch creation and cut the tag directly from 2-6-x in order to keep branch management (i.e., merges) at a minimum.
The advantage of working from a 2.6.0 branch rather than from the *x branch is the greater control one can exert on what ultimately ends up in the release. Recall that 2-6-x .externa ...