Today, the much anticipated Python 3.0 final was released. Truly, this is a historic release for the Python community, the first intentional incompatible Python release. It's been a long time in the making, and I applaud everybody who is responsible for proving Py3k is not vaporware. Guido and the other decision makers on Python-dev also deserve credit for not making py3k changes too gratuitous; many revolutionary ideas and features were proposed and rejected. I have every confidence that every incompatibility was well thought out. Much thought has also been given to making the transition as easy as possible for the community. The suggested migration path, fixing Py3k warnings in 2.6 and then applying 2to3, has been used with a fair amount of success on several projects. We've even had several Py3k love letters!
Still, I can't help being a little worried. I think the bytes and str divide will be difficult for people especially with IO where everything has to be dealt with in bytes. We may see many "x.encode('ascii')" lines popping up all over codebases. Userland libraries will need to maintain compatibility with 2.4 and 2.5 for a while; that significantly complicates the dream of maintaining just one branch for 2.x and py3k. 2to3 is not even close to perfect and will only correct the surface incompatibilities of syntax between the versions. I'm also concerned about burn out. The excitement of a new major version will certainly spur an interest in porting for a few months, but I suspect it won't be so fun after the aura wears off a bit. I hope common base libraries (PIL, Twisted, lxml, etc...) are ported soon. It will build the bridge for everything else to cross over too.
Of course, what I'm forgetting is the amazing Python community. Whatever the results, a new era has certainly begun. We just need time.