Platform: Mac OS X Server
Developer preview, not public retail availability.
Apple source ↗Apple unveiled a developer preview of Snow Leopard Server on June 8, 2009, initially planning September availability. Its August 24 announcement brought the planned availability forward to August 28. Both stages matter: the first announcement was not public retail availability, and the initial forecast is not the final date.

Apple · Server 10.6 · 2009-06-08 · Apple · Server 10.6 · 2009-08-24
Mac OS X Server 10.6 added Podcast Producer 2 and Podcast Composer for automated production and publishing, Mobile Access Server for access to internal services, and CardDAV-based Address Book Server. Wiki Server 2 and iCal Server 2 expanded collaboration and calendaring; NetRestore restored images over the network. Apple described a 64-bit system compatible with 32-bit applications, without its speed tests guaranteeing the same result on every server.
Apple · Server 10.6 · 2009-06-08
The US $499 edition included unlimited Mac, Windows and Linux clients; this was not the $29 client upgrade. Apple required an Intel processor, 2 GB RAM and 10 GB free, excluding PowerPC servers. The $9.95 Up-To-Date offer had specific qualifying-new-Xserve and request-deadline conditions, not universal eligibility for every Leopard Server owner.
Apple · Server 10.6 · 2009-06-08 · Apple · Server 10.6 · 2009-08-24
In Macworld, John C. Welch praised the new features and home-directory synchronization, but found CardDAV and CalDAV use less consistent with non-Apple clients. He advised more caution for mixed networks than for mainly Mac environments. These were conclusions in his October 2009 review, not a description of current support or clients.
John C. Welch · Macworld · 2009-10-15
Selected releases, not a complete history. Dates follow Apple's release records, not the latest page edit. No builds are included.
ISO date: year-month-day.
Platform: Mac OS X Server
Developer preview, not public retail availability.
Apple source ↗Platform: Mac OS X Server
Availability announced in the later release; supersedes the September forecast.
Apple source ↗