The term 'Cross-Platform' has become common place. For me this term is now and always has been redundant. There is a certain lack lustre feeling I get when I hear it because this is surely the shortfall of bad creative?
Speaking from the point of view of Brand; All creative output is set to serve the brand and, as such, their client base. If an asset is developed as part of a project, the baseline concept at the heart of this campaign should work across all platforms, streams + in any form of dialogue. The term may of course be over used due to a misunderstanding.
Cross-platform is of course an appropriate description when used to describe digital offerings that need to adapt across multiple devices. This adaptability has become a necessity in web design to allow mobile devices to effictively utilise the same brand offering as any desktop work space. But when it comes to content, content should have been and always needs to be built to communicate across multiple streams. This is nothing new, but I feel it is viewed as being something to have arrived in the digital age.
This leads me on to the broad ethos of what 'cross-platform' encompasses. When used correctly; it calls for the planning, content, interface and service to be effective through all streams. But this building of such a business element takes more time than most commercial timescales and budgets currently effectively allow for, in my opinion. It's a similar behaviour to the old notion that building a brand is a simple design problem (Logo, Message, Identity, Marketing...). This building of a successful brand takes time, finesse, trial & error, engagement and most importantly an ongoing evolution.
So instead of looking at platform building as the key to all business needs, start looking at the baseline brief again. Identify the brands' need, then look at the final message that needs to be delivered. Develop that story without a platform even in mind... Only then will adding a medium of delivery to that idea deliver the kind of unified, cohesive, cross-platform communication that the brand requires. Avoiding dilution, maintaining continuity no matter how many streams are needed.