At the beginning of 2010, the Google Wave team's UI designer, Cameron Adams, took the learnings from two years of Wave development and applied them to a refreshed design of the Wave client. We are sharing these designs here with the hope that they may help inspire future development of the client by the open source community.
These include ideas regarding search, chat, contacts, inbox management and content separation. The Wave in a Box project won't fully implement all the elements in these ; however, we welcome anyone in the open source community to implement them or build on them.
As part of the Wave in a Box project, we have released the new "undercurrent" wave panel as planned. It also includes some new UI elements (new borders, indenting, etc). See http://www.waveprotocol.org/protocol/design-proposals/new-wave-panel-undercurrent.