I would love to have some basic formatting abilities in Task Notes.  The biggest ones are:

• Font
  • Particularly size
  • Bold / strikethrough / italics
• Colour
• Bullets
• Highlighting

Perhaps HTML or RTF.

Not sure of the consequences / complexities / considerations in doing this, particularly with regards to MS Project compatibility.  Although I would love to see (as another poster put it) ProjectLibre be "superior to MS Project", not just compatible.