The OP appears to be surprised that a minor-release upgrade (which added some nifty features, basically broke zero existing code, and allowed trivial rebuilds of all existing third party libraries) happened overnight at their organization, while a major-release upgrade (requiring much more effort especially from the point of view of third-party library authors) didn't and won't. I think I mostly feel surprised at their surprise;-).
Even minor-release upgrades don't happen instantly in most large projects and organizations; for example, App Engine is still using Python 2.5 (apparently, upgrading its specialized "sandboxed" Python runtime and all it relies on is not a zero-effort proposition, so they prefer to keep putting their energy towards adding engine features instead) -- so I believe are implementations such as Jython and PyPy (I think IronPython's in the process of migrating to 2.6, but the current production version is still 2.5).
Totally new projects starting today should seriously consider starting with Python 3; for example, Allison Randal's pynie (Python for Parrot) project made exactly that choice (and, I think, it was the correct choice in their situation). Migrating existing projects is a harder proposition, and mostly depends on what third-party components the existing project depends on (if a new project intrinsically depends on some functionality that's only available in 3rd party libraries for 2.6, not 3.1, then the new project will probably also have to stick with the 2.6 version for the time being, of course).
Third party libraries that are under active development will probably come out with Python 3 version gradually (for example, gmpy did so relatively recently). Once enough such third party libraries are available, the chance that a missing library inhibits migrating an existing project (or, even more, starting a new project) using Python 3 starts going down pretty rapidly. This makes Python 3 ports feasible. At some point, some attractive functionality will become available in Python 3 only (for example, if and when pynie releases, that might be the case for a Parrot implementation affording smooth interoperability with Perl &c), and that will provide a strong motivation for some projects to go 3-only (pragmatically stronger than pure issues of language quality).
Even then, some sufficiently large projects and organizations will stick with Python 2 for a long time, and you can confidently expect that at some time a 2.7 will exist (possibly one or two more after that, but that's harder to predict). Hey, I sharply remember that throughout the '90s in most large projects and organizations "Fortran" still meant Fortran 77 (in fact in some places -- not many, 30+ years after than Fortran version's first release -- that's still true today!)... for all the advantages of Fortran 90 and later versions, migration costs (esp. in terms of various compilers, libraries, tools) were just perceived as being too high a price to pay for the advantages of the new language version. That's just inevitable when a language acquires a large installed base and a rich ecosystem of third party tools and libraries, as Python 2 now has. No reason for surprise!-)