A Darwinian opening
On the 16th of March 1999 Apple announced Darwin, the open source core of Mac OS X.
While the product was actually released more than an year after, on the 5th of April 2000, the move signalled a big change for Apple, which openly embraced the open source movement after the false start of MkLinux a few years before.
The announcement of Darwin (and of an open source version of QuickTime Streaming Server) was closely related to the the first version of Apple’s NeXT generation operating system, Mac OS X Server, announced in January at Macworld.
So in March, just a few days apart, Apple shipped both its new server operating system and at the same time released freely many of its core foundations.
Darwin’s birth and Apple’s push into the open and free world were initially met with mixed reaction, with many people not knowing whether or not to trust Apple’s motives and the Apple Public Source License (APSL) chosen for the source code. 
The license was modified at least three times and only in 2003, after being already accepted by the Open Source Initiative as an “open source license” it also gained the “free software license” status by the more stern and orthodox Free Software Foundation.
The Cupertino company eventually began to get acceptance of its open efforts, adding through the years many projects such as Bonjour/Zeroconf, WebKit and Calendar Server to mainstays Darwin and Darwin Streaming Server enduring to this day a fruitful although occasionally rocky relationship with the open source community.
Ten years ago: here comes Mac OS X Server
On Jan. 5, 1999, during the Macworld Expo, Apple announced Mac OS X Server as its’ new server operating system offering, which was declared to combine “the proven strength of Unix with the simplicity of Macintosh”.
Apple’s software lineup in 2001
In 2001 Apple was still at the beginning of its slow transition from the Mac OS 9 era into the X one and also building up what would become a prominent role in the desktop video market.
In may of that year a promotional video was released in which Steve Jobs showed off the first Apple Store: in the last part the camera pans on the aisles and we can take a look at the main software offerings from Apple, still a mix of classic product lines and solutions coming from the NeXT acquisition.
From left to right you can see boxes of Mac OS X 10.0, Mac OS 9, AppleWorks 6, Final Cut (Pro) 1.2.5, AppleShare IP, AppleCare while in the lower part are Apple Media (blank) CDs and WebObjects 5.