Slices are still on sale on fiveninjas.com but there's very little activity in this forum, very little or none over the past few months in the software repos on Github, bugs are not being triaged, and the latest stable build is from March. The "LED App" stretch goal never appeared.
There are still problems which prevent Slice being a "plug and play" solution (on mine, the /storage partition fills up regularly, for example, which brings everything to a screeching halt, and needs to be fixed via SSH).
Even during the days of activity, it did seem like Slice was a side project for some of the key Ninjas, in addition to the day job. Is anyone still working on the Slice? Are there any plans for future software or hardware (RPi 3?) updates?