Since open source projects are different from traditional "competitors", we get to see lots of great camaraderie like this between them. One of my dislikes about Drupal has always been the release cycle and accompanying breaking of backwards compatibility.

While I understand that ignoring BC can allow you to make big changes more easily, it sure makes things harder on your user base. I have to wonder how many sites out there are still running on Drupal 6.x, or even 5.x, because site owners didn't have the resources (expertise and/or money) to convert to a newer version.

It sounds like Drupal might be taking an approach that will tone that down, while not discounting the possibility of BC breakage. Which I think is perfectly reasonable.

It's not like WordPress has never broken BC. I'm sure there are plenty of themes and plugins written years ago that would not function properly on the current core. We just break things much more gradually, usually by adding new functions, and deprecating old ones so that they still work (as much as possible), but spit out warnings in the logs.

Anyhow, great to see some cross-pollination between projects!