This terms is often used with many meanings.  For example, some people consider Flash 'open' and 'multi-platform' .  But Flash is a product of Adobe systems, locked down, copy protected and distribution restricted.  And versions for other than standard PC, home use, may carry licence fees.

Check it out:

3.1 Adobe Runtime Restrictions. You will not use any Adobe Runtime on any non-PC device or with any embedded or device version of any operating system. For the avoidance of doubt, and by example only, you may not use an Adobe Runtime on any (a) mobile device, set top box (STB), handheld, phone, web pad, tablet and Tablet PC (other than with Windows XP Tablet PC Edition and its successors), game console, TV, DVD player, media center (other than with Windows XP Media Center Edition and its successors), electronic billboard or other digital signage, Internet appliance or other Internet-connected device, PDA, medical device, ATM, telematic device, gaming machine, home automation system, kiosk, remote control device, or any other consumer electronics device, (b) operator-based mobile, cable, satellite, or television system or (c) other closed system device. For information on licensing Adobe Runtimes for use on such systems please visit http://www.adobe.com/go/licensing.

You will notice, for its embedded operating systems, Microsoft buys and includes a fully paid license for Adobe.   Do you get this with Linux?  Unix?  QNX?

So, what is 'open'?