As previously discussed, Composer is slowly moving into the Drupal world. While D8 is in alpha (just) it's still too early to say Composer and Drupal are best of friends; but it's a sign of the times when crell writes in Drupal Watchdog all about our brave new Composer future.
With that in mind, I'm really pleased to announce a new release of Drush instance: 7.x-1.2 includes improved class-based handling of both file management in a build, and also exceptions arising from build problems. But most importantly, Drush instance now offers basic support for a composer.json instead of a makefile.
Right now I use Drush instance for deploying my own site, and I know of at least one other company that does so, using a makefile. But now Drush instance supports composer.json, I'll be using drush m2c to convert my own makefile to composer.json, and trialling that as a way of (re-)building my codebase whenever I need to make updates to it.
There's a lot to be done in Drupal development, to move away from all our cherished Drupalisms (which supported our best practice for years when nothing else could quite do the same thing), but hopefully these transition technologies will go some way to easing the path to a brighter, standards-friendly future: if and when any one developer wishes to follow that path.