Via the World Wind Wiki, new features in the latest release are as follows:

Exciting new uses for exploring our world and beyond.

Mars: In addition to the Moon which debuted in 1.3.3, we now have Mars with full 3D terrain.
see TServo's Blog post I give you Mars (http://alteviltech.com/blog/2006/02/24/i-give-you-mars/)
SDSS: View the galaxy with outer-space imagery from the Sloan Digital Sky Survey (http://cas.sdss.org/dr4/en/)
see TServo's Blog post Sloan Digital Sky Survey Images in World Wind (http://alteviltech.com/blog/2006/03/25/sloan-digital-sky-survey-images-in-world-wind/)
Venus: 3 image layers without 3D terrain + placenames
Jupiter: Jupiter and 4 Moons + placenames

New Plugins

Movie Recorder: Movie recording script. Plays back a script file with camera positions and records each frame to sequentially numbered bitmap files on disk, via Mashi
Measuring tool: measure distances/bearings on the globe, via Mashi
Starfield: adds a dynamicaly rendered starfield background to World Wind using data from the Hipparcos catalog, via Patrick Murris
Compass Rose: renders a compass in World Wind, via Patrick Murris
Clock: On-screen clock, via Mashi
Earthquake Plug-In: Near-Real-Time Earthquake display and Historical Earthquake Query, via Chad Zimmerman
KML Importer: Import Placemarks from KML and KMZ files, via ShockFire

Updated Imagery

OnEarth (http://onearth.jpl.nasa.gov/) 15m Landsat imagery
Improved elevation data based on SRTM+ and SRTM

Any many other features and fixes - See here for Details