The BBC News website has an article up regarding a conference talk given by the Huygens SSP Principal Investigator John Zarnecki at the UK National Astronomy Meeting. He reported that based on test drops run at Open University in Milton Keynes, the probe likely landed on one of the fist-sized pebbles strewn across the Titanian landscape before slipping into the icy sand. Shortly after the probe landing, the SSP investigators reported that the penetrometers results were consistent with a surface that consisted mostly of sand-sized particles covered by a thin crust. This led to the early analogy developed by Ralph Lorenz of the SSP team (and the principal developer of the penetrometer component) of creme brule. While the hard crust-sandy middle model has not been ruled out, from the article:
"A crust is still a possibility, but we now think it's most likely we hit one of those water-ice pebbles you see in the ground image; the biggest you see is about 15cm," Professor Zarnecki told the BBC News website.
"We probably pushed the pebble to one side and then ploughed into the stuff underneath which we are pretty convinced is a 'sand' made of ice," the principal investigator on the Huygens surface science package explained.
The article also reported that the penetrometer results were consistent with a matrix of sand- to gravel-sized particles up to 8 mm in size.
Thanks to paxdan over at the Unmanned Spaceflight forum for the link.