Autocutsel synchronizes the two copy/paste buffers mainly used by X
applications. It unifies "clipboards" between VNC servers and Windows.

The 'cutsel' binary performs the synchronization whenever it is run.
The 'autocutsel' binary performs the synchronization continuously.  I
suggest running it from ~/.vnc/xstartup by adding a line like this at
the top:
  exec autocutsel &

WWW: http://www.nongnu.org/autocutsel/