See also: Collaborate With Chemistry.se?
Many of the newer sites have a certain degree of overlap.
With the creation of Chem.SE, I noticed quite a few questions on Physics.SE which could have benefited from the chem community and vice versa. There also are a few that could benefit from bio.SE..
Now these questions don't warrant a migration. They can be double-posted, but this doesn't lead to a smooth experience. Even when cross-linked, changes to either post (new answers,new comments,etc) aren't effectively relayed to the other site, and the two questions are just that-- two, separate questions.
One solution that came to my mind was a "soft migration" option for mods. By this, a question on site A stays on site A. But, it appears in the site B question list as well. Edits/answers should bump it.
Basically, there will be a placeholder item in the questions list of site B. It shows the votes/views/answers of the post on site A, along with the tags (maybe stylized differently). These should be an unobtrusive way to quickly identify what the site is.
The post should also be bumped whenever the post is bumped on Site A, and it should display the rep/time/etc of the bumping user as usual.
Here's a quick mockup of what happens on the site B question list:
Without being obtrusive or in-your-face (stuff like
[migrated] is sort of in-your-face), the post is elegantly shown to be on Physics.SE (well, if you know the icon, anyway). The tags are italicized to show that they link to a different site tags, and the "bumping user" (me) has his/her rep on that site shown. We can also add an indicator on the question on site A (like this) that shows that it was soft-migrated. We can use tooltips as well on the icons to tell us why they're here. After all, half of SE documentation is in tooltips.
Now I know that these issues will probably be raised:
Rep: An avid user on Site B gets no Site B rep for giving a good answer on Site A. Frankly, I don't care about this to much, but others may.
Implementation: It may get complicated. Internally, I'd propose that none of the question data is copied, rather Site A pushes the vote/bump data whenever a vote/bump happens. The easiest way to then implement the soft merge would be to have a table of questions soft-merged "to" site B on site B itself, with columns for all the vote/etc data. The questions table should have an extra column for "soft-migrated to"--that way Site A can determine where to push new data to on every vote/bump. Now, all Site B has to do is take the
JOINof the questions table and the soft-merge table and display them in the new questions list (or any list, for that matter). With some extra formatting, maybe. Of course, I may be oversimplifying this and I don't really know what I'm talking about ;-)
Is there a need? : Yes, I would say so. Such questions can get awesome answers is both the communities participate, but our don't-cross-post-much policy deters this. In the end, this will result in better post quality, making the Internet better. Also, as area51 grows, we will see this problem more and more, and this will become more and more necessary.
Thoughts? Any better ideas? Waffles?
Update: Another use case for this would be to soft migrate all MSO faq questions over to child metas, effectively solving Make network-wide FAQ posts available on per-site metas