Platform Agnostic today means that my system can work with your system, and it doesn’t really matter what we use – it will always work the same way. I used to use this term a lot on SEM sales calls to describe how interoperability was possible regardless of the systems being used.
I have started using this term today to describe and talk about web applications and companies as they grow beyond what their original intent was and mature into something better.
Many things can get in the way of a user experience going the way you intended it to (Air apps, multiple browsers, different operating systems, variable bandwidth connections, mobile browsing, and more)
Being platform agnostic means you rise to the challenge of a non-standard configuration and deliver your intended behavior or experience without any trouble. It shows you are ready to scale, designed for what comes next, and prepared if attention shifts to a new platform.
Be platform agnostic.