This past weekend, Cassini sampled the particles in the plumes visible near the south pole of Enceladus. No chemistry results have been released yet, but if we're looking for interstellar replicators (von Neumann probes or otherwise) that build themselves out of common native materials on low gravity bodies, this is exactly the kind of research that's going to start finding interesting results. This is probably my most absurd belief - that there are artifacts of alien technology already here in this solar system, and we're going to find them on wet, low-gravity bodies like comets or Enceladus - but that's why I'm excited to get data that tests this prediction. If all that spray is just cold saltwater, that decreases the chance that we're going to find organic chemistry-based replicators anywhere else outside the Earth's atmosphere - but we already know there are simple organics in the plume, along with higher mass hydrocarbons. I don't know if Cassini's instrument can distinguish between higher mass hydrocarbons or (for example) amino acids, like those found on meteors and comets.
On a side note, this event has gotten amazingly little press outside the science blogosphere: a space craft flew over a moon of Saturn, straight through a water plume from an ice volcano, to sample the chemistry of that water - and indirectly, the probable oceans under the crust. That's pretty incredible.
Above: the Tiger Stripes on Enceladus, where the spray is thought ot originate. Below: the San Francisco Bay Area, from the same altitude (about 115 miles), just because it's cool to compare.