API 0.6 is scheduled to go live on 17-19th April, 2009.

この週末API 0.6へのアップ作業が行われています。17日現在OSMはRead Onlyとなっていて編集はできません。
エディタ（Potlatch 0.11、JOSM v1529、Merkaartor v0.13）も変更があるようです。JOSM v1529は既にダウンロード可能でした。Potlatch 0.11はどう変わったのか楽しみです。
サイト画面に登場するhistoryタブとは・・・。

API 0.6 is scheduled to go live on 17-19th April, 2009.
You might not even notice that things have changed. A lot of the work is going on behind the scenes, but the most important things aren't changing - there's still nodes, ways and relations, and we're still using the same key/value tagging. The main thing that has changed is that all your edits will be grouped into "changesets", and in most editors you can supply a commit message - an optional string explaining what mapping you were doing.
Other than that, you'll notice a few cosmetic changes to the website. The biggest change is the new "history" tab, which uses the new changesets to show you who's been editing in a given area.

http://wiki.openstreetmap.org/wiki/OSM_Protocol_Version_0.6/Information