Version 1.11 has just been released. It drastically improves stability and domain support while simplifying the initial interface, adding up to four signatures per address, and giving you more options to customize your experience.

• Version 1.11 (released July 17, 2008)
  
  • Further improved stability
  • Cleaned up buttons so that there are only two now (create/edit and options)
  • Increased support for Google Apps with custom domains
    
  • Added support for up to 4 signatures per address
  • Added options to customize the labels for the 4 signature slots (e.g. "Default", "Personal", etc.)
  • "Reinsert" signature button is now hidden by default with option to show it
  • Added useful links to options window
  • Added promote & support information to options window
  • Moved "Donate" button to options window

Check out the updated Getting Started page for more details.