v0.4.0
* Introduced standby mode
* Added HEAD requests
* Set logs NOCOW flag when BTRFS is detected to avoid fsync overhead
* Fix all known data races, and pass Go race detector (TODO: re-run race detector)
* Fixed timeouts when using HTTPS
* Improved snapshot stability
* Migration of machine names to new IPs
* Updated peer discovery ordering

v0.3.0
* Add Compare-and-Delete support.
* Added prevNode to response objects.
* Added Discovery API.
* Add tracing and debug endpoints (Documentation/debugging.md).
* Improved logging of cluster events.
* go get github.com/coreos/etcd works.
* info file is no longer used.
* Snapshots are on by default.
* Statistics APIs documented.

v0.2.0
* Support directory creation and removal.
* Add Compare-and-Swap (CAS) support.
* Support recursive GETs.
* Support fully consistent GETs.
* Allow clients to watch specific paths.
* Allow clients to watch for key expiration.
* Unique key generation.
* Support hidden paths.
* Refactor low-level data store.
* Modularize store, server and API code.
* Integrate Gorilla Web Toolkit.
* Add tiered configuration (command line args, env variables, config file).
* Add peer protocol versioning.
* Add rolling upgrade support for future versions.
* Sync key expiration across cluster.
* Significantly improve test coverage.
* Improve migration testing.
* Configurable snapshot count.
* Reduce TCP connection count.
* Fix TCP connection leak.
* Bug Fixes: https://github.com/coreos/etcd/issues?milestone=1&state=closed

Contributors:
* Xiang Li (@xiangli-cmu)
* Ben Johnson (@benbjohnson)
* Brandon Philips (@philips)
* Yifan (@yifan-gu)
* Rob Szumski
* Hongchao Deng (@fengjingchao)
* Kelsey Hightower (@kelseyhightower)
* Adrián (@adrianlzt)
* Antonio Terreno (@aterreno)