Downloading core via command-line
drush dl drupal-8


Since there are no stable releases of Drupal 8, you must use the --all option to see the tagged alpha releases:

drush dl drupal-8 --select --all


This also works.

drush dl drupal --default-major=8 --select --all


Both of these are now working in the current version of Drush, without the --all flag:


drush dl drupal-8 --select
drush dl --default-major=8 --select


Note that the Drush pm-* commands only work with one major version of Drupal at a time, and that version currently defaults to Drupal 7. Therefore, drush dl drupal only shows the various Drupal 7 releases available, and does not include any versions of Drupal 8. This much has not changed.

drush dl drupal-8 now works fine with the Drupal 8.0.0-rc1 release.