すでにいくつかのサイトで触れられていますが、Firefox 3.5の正式リリースは6月末日(日本時間で7月1日未明?)を予定しているとのことです。それに先立って、19日(日本時間の明日未明)にRC2がリリースされる予定。RC1はベータ版からのアップデートのみでしたが、RC2は一般公開されるようです。
Firefox 3.5 release candidate builds: new and exciting! - mozilla.dev.planning | Google Groups
On June 19th, we hope to release (on our website, as a full download)
a release candidate. Right now that would be the rc2build2 version, as
it's the latest thing we have. So, in other words:
June 16th: Firefox 3.5 beta users get updated to an early release
candidate (rc1build2)
June 19th: Firefox 3.5 beta users get updated to the official release
candidate, which is also put up for direct download (right now this
would be rc2build2, but that may yet change!)
end of June: target ship date for Firefox 3.5