I've just uploaded v0.621 to SourceForge. Several bugs have been fixed, some new content has been added, and the readme file has been greatly improved. Here's a list of highlights:
New Story Content: There are now multiple ways to meet your core story enemy, and depending on how the story goes your initial enemy may even be replaced with a better one. There are also more *CORE_INTRO components and a greater variety of starting missions. For the time being I'm going to work the content from the two ends: more variety for the beginning of the game, and some special scenarios for the end. The middle bits can wait for now.
Debriefing: After completing a core story mission, the NPC who sent you will sometimes comment on whatever happened. This seems to be working well so far; it gives the core story episodes a sense of coherence that they were previously lacking.
Better Directions: When giving directions, NPCs should now use an unambiguous place name. For instance, they won't say "He's in Cayley Rock", but instead "He's in Cayley Rock Main Station". Note that this will only come into effect when you start a new campaign in v0.621; campaigns from v0.620 will run perfectly fine but you'll still get the ambiguous place names.
Ersatz Mouse: If the mouse isn't visible, activate this config option to use the game's built-in mouse pointer.
NPCs can tell PC to buzz off: If they really don't like you, you'll get a "buzz off" message instead of the random chatter.
Title Screen: And someday we'll get an even better one.
Fixed Bugs: BuildRobot prints the correct message, world map travel works in 2D, Mullins is now visible, props without defined sprites now have one, Create Pilot works in ArenaHQ, monologues should not cause the game to crash.
As usual, try it out and let me know what you think.