Comment 2 for bug 1577219

If I had to guess, I would say that screenlets was removed because of some dependencies on Python 2. (Ubuntu is trying to move away Python 2 and toward Python 3.)

It looks like the screenlets package existed in Ubuntu 16.04 for a bit was remove sometime before the launch: http://www.ubuntuupdates.org/package/core/xenial/universe/base/screenlets

I tried to install the package of screenlets for Wily Werewolf from these locations:
http://packages.ubuntu.com/wily/screenlets
http://packages.ubuntu.com/wily/screenlets-pack-basic

I got the following errors:
dpkg: dependency problems prevent configuration of screenlets:
 screenlets depends on python-support (>= 0.90.0); however:
  Package python-support is not installed.
 screenlets depends on python-gnome2; however:
  Package python-gnome2 is not installed.
 screenlets depends on python-wnck | python-gnome2-desktop; however:
  Package python-wnck is not installed.
  Package python-gnome2-desktop is not installed.
 screenlets depends on python-beautifulsoup; however:
  Package python-beautifulsoup is not installed.

dpkg: error processing package screenlets (--install):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of screenlets-pack-basic:
 screenlets-pack-basic depends on screenlets; however:
  Package screenlets is not configured yet.
 screenlets-pack-basic depends on python-support (>= 0.90.0); however:
  Package python-support is not installed.