Working on a wildly hacky Tweet importer for preserving/continuing conversations. It writes directly into the backing Mastodon database so it's really only an option for self-hosted users.
My first import: https://mastodon.jakewharton.com/@jw/85157730779175614
Had all kinds of problems inserting directly into the Mastodon DB. For some reason links weren't becoming linkified (this is separate from the preview card).
I switched to patching the Mastodon app to allow creating statuses with a timestamp through the API: https://github.com/JakeWharton/dumbo#modifying-official-mastodon. The idea came from someone else's import tool: https://github.com/lucahammer/fediporter.
Links now work, and we get all kinds of things for free like those link preview cards. Support for media and threaded replies are up next.
@jw can you also theoretically add posts into the future?
> The Mastodon API does not allow inserting posts in the past. In order to write statuses which occur in the past, a created_at parameter is needed.
Could something like that also then share to other servers? I would hope there's a failsafe for that 
. That could really weird up some timelines.
@jw That was my thought too. I would expect it to behave like some kind of ultra sticky toot.
And likely other instances couldn't easily deal with it either, since only you can delete your toots (being the instance owner).
People would need to patch their instances and or ban misbehaving instances.
A fun thought experiment in any case. I look forward to your findings
