Meanwhile, two points of note:
1) In weave the IP addresses can be much "stickier" than in other network setups, i.e. a moving a container from one host to another can retain the containers IP. That means it is quite amenable to relatively static name resolution configurations, e.g. via /etc/hosts files.
2) Since weave creates a fully-fledged L2 Ethernet network between app containers, name resolution technologies like mDNS that rely on multicast should work just fine.
So, in summary, while weave currently does not have any built-in service discovery, existing solutions and technologies for that should be relatively easy to deploy inside weave application networks, until weave itself grows these capabilities.