Modern OS =
Ability to play every kind of digital media format for Audio/Video/Images/Text
Ability to surf the internet/design sites with every defined standard for page definition supported in your browser available.
Ability to download and upload data via peer-to-peer network standards
Ability to use SKYPE/MSN networks for chat/video chat.
Ability to use a sophisticated office suite (WP/SS/TM/EC)
Ability to display 3D with a graphical sophistication >= PS3/360 @ 1080p
Ability to connect to all mass produced add-on hardware types (USB MP3 players/cameras/Webcams etc)
Ability to run the majority of applications currently sold/freely downloadable etc
IMO that's what it means. ie it does not impede your use of the computer via the choice of OS you have chosen to use. Sure NextSTEP 3 can run your business just as well as a host of Windows based networked computers but that's why it's such a meaningless phrase in some cases. There are things NextSTEP does that Windows 2008 still does not, useful things too.
