Though I'm a little late on this thread (late-night class and slept in), I want to provide my arguments for the timestamp-update issue.
Seekers of Perl Wisdom is a high-traffic area. Many monks have told me that they generally ignore Categorized Questions and Answers, even though its posts appear in Newest Nodes. When someone mistakenly posts a question to Q&A (because the problem is far too specific to belong in Q&A), (s)he needs an answer.
Though I attempt to be very responsive to Q&A (and other Q&AEditors do, as well), I often wander across a misplaced Question many hours, or even a few days, after it was originally posted. There are often (usually?) no answers to that post, in spite of its age. When I have moved those questions to SoPW, manually, they almost always begin to receive responses immediately. Where there had been no traffic in Q&A for hours/days, there is now immediate traffic in SoPW because it is at the top of the Newest Nodes list.
My concern about timestamps is related to this phenomenon. As it currently stands, the relocated question will appear in the Newest Nodes list (usually) "buried" below more recently created nodes. This will cause many of our most responsive, helpful, knowledgeable monks to miss the question. Many monks will never see the question at all, because the most recent "I've checked all these" timestamp will be later then the creation date of the Q&A post.
If the timestamp on the relocated question were updated to the "moved" time, the question would appear at the top of Newest Nodes, garnering all the attention and expertise that Perl Monks has to offer.
Since most mistakenly Q&A'ed posts are made by newbies, I feel that this change would preserve the helpful reputation of PM. Questions that are misplaced will not just silently disappear, never to be answered. Instead, the full force and fury of Monks' expertise will be brought to bear on the question, with only the erroneous placement silently corrected.
Many thanks to vroom for this feature. I have wanted this for quite some time, and when Tim became aware of the need, he implemented and rolled out the solution in just a few hours. Once again, vroom, you are the man!