Really Big Sky 5.01 has been pushed out to Steam and there are some nifty new features;

• Increased brightness of starbits
• Disabled automatic window alignment
• Force the game to run in low settings by adding "low.txt" to your game folder. This overrides any other options! Good for troubleshooting and picnics.
• Cursor now locked to game window during gameplay
• Steamworks Achievements added
• Slowed down difficulty build up for all modes
• Decreased event generation rate for all modes
• Reduced vibrations (both intensity and duration)
• Fixed a bug on the name entry screen
• Built on Clickteam Fusion 2.5, so there could be minor, non-specific improvements here and there. It only came out a week ago!

(Bolded my favourites :))

Any achievements you have unlocked in-game will be synced over to Steamworks achievements.