These are the presentation notes from a "Migrating into Drupal 8" presentation I did at DrupalCamp Toronto 2014.
This discussion is focused on introducing the new concepts behind the new migration system that replaces the historic upgrade-in-place system we have used in previous versions.
Since many of these items are works in progress they are subject to change!
If you are working with D8 migrate now, keep in mind you will probably have to re-migrate at some point until the migration path is finalized. This may not happen until 8.1.x or even 8.2.x. It depends greatly on testing.
It is critical that as many people test the migration path as possible. Especially with sites that have been upgraded previously as those are likely to have the most problematic edge cases.
Currently the migration path in Drupal core is D6→D8, with D7→D8 in progress. The UI needs a patch and/or the "imp sandbox" version of D8. The UI will probably be in place around the time of DrupalCon Austin in June 2014.
Links to the initiative and places you can contribute are listed in the presentation.