Piano music is always typeset in two staves connected by a brace. Printing such a staff is done similar to the polyphonic example in Combining music into compound expressions:
<< \new Staff { ... } \new Staff { ... } >>but now this entire expression must be interpreted as a
PianoStaff
:
\new PianoStaff << \new Staff ... >>
Here is a full-fledged example:
More information on formatting piano music is in Piano music.
This page is for LilyPond-2.0.1 (stable-branch).