Stable chaos in the 55Cnc exoplanetary system?
  The five planets discovered around the main-sequence star 55 Cnc may represent a case of stable chaos. By using both the Frequency Map Analysis and MEGNO we find that about 15 % of the systems that can be build from the nominal orbital elements of the system are highly chaotic. However, in spite of the fast diffusion rate in the phase space, the planetary system is not destabilized over 400 Myr and close encounters between the planets are avoided. 
Julie Gayon, Francesco Marzari, Hans Scholl