I have been following the discussions on ubuntu-devel, -devel-discuss and -launchpad-users mailing lists regarding the status of Ubuntu bugs. There are many different discussion threads, some of them cross-posted, so it is a little difficult to give all the links (and I may forget one, which I do not want to do).
One particular bug I followed was marked “expired” and I realized I did not understand the different statuses in Launchpad.
Matthew Revell has posted a summary of what happened to all the incomplete bugs earlier last month, and most important, an updated documentation will be available and easier to find for basic contributors such as me.
For now, you can check the Launchpad blog post, which I had not been talking about so far, I was waiting for more infos on the mailing-lists.
Many thanks for all this work!