The Debian Project neither sets nor adheres to defined release dates for its GNU/Linux distribution. Basically, they have the “we'll release when ready” philosophy, and given that a version of Debian that has been designated as Stable actually does mean something to users, I'm fine to wait.
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I've been using Debian Lenny currently Debian's Testing distribution for quite a few months now. And while I have my issues with Lenny on my Gateway laptop, just about everything works. As far as features go, Lenny represents quite a leap from Etch, especially on the desktop.
One thing about Testing, as opposed to Stable, is that there are lots of updates to download and install. If you are OK with that, it's not annoying, but it's nice for me to boot my current Etch box (a Power Macintosh G4) and know that I won't have 50 packages that need updating. Usually there are no updates at all.