Intriguing post, but for some vague reason their approach sounds overly complex.

I haven't thought about this in any detail but the problem they're trying to solve with Signal is allowing you to search and filter your social/professional stream, but I suppose the volume of data they're dealing with super high which is why they need faceted search and a "distributed realtime searchable database"

Or perhaps it just sounds complicated because there's way too many buzzwords in the post.

The distributed messaging queue (Kafka) sound cool though.