The new thing Yahweh is doing is causing Israel to be liberated and saved by Cyrus of Persia, a foreigner. Not a king or liberator from within the community, such as David or Moses, but an outsider. It is Cyrus who allows the exiled Hebrews to return to their promised land. This is often seen by Christians as a precursor to the new thing God does in sending Jesus. Doing a new thing is lifted up as good, exciting, and important.
Liberation can come in unexpected ways.
Doing a new thing is something we all have to undertake once in awhile. A new thing, an unexpected course. There is a force at work in the world spurring us forward to new possibilities. The human imagination is a marvelous gift. We can imagine a new and different future, and it excites us.