Hello,
There have been no recent efforts to do this.
That said, we would love to see the necessary work happen to re-integrate the two (they used to work together).
The main issue is that Serval now uses its own VoMP (Voice over Mesh Protocol) instead of SIP+RTP for voice calls, and uses its own DNA (Distributed Number Architecture) instead of IP-based numbers.
The servald process does include SIP gateway functionality, so it would be possible to add servald to a mesh potato, and integrate it there. With some extra effort, it would be possible to completely replace Asterisk by writing a VoMP channel driver for the MP. But it really depends on what the objective is.
Paul.