It's one of the key points we were proposing during the ICE workshop within our work group... We must allow the user to use her own combination - cocktail - of tools for accesing the "collaborative" platforms and services we will be providing them within and/or outside the corporate borders.
In order to do that, I'm pretty convinced that what we need is to use the tools and de-facto standards we currently have in place for 'empowering' the user in her own strategy for building up her own personal collaborative environment (pce).