There has been a silence on the site over the last few weeks (months), but things have been progressing. The web search use case is operational and running in full swing for some weeks now. We will have more updates on the other two use cases very soon.
You can still sign up for CLEF until April 30. Note that the deadline for submitting official runs is April 15.
We have also prepared a guide specifically for CLEF participants; this should help you to get started right away.