The gist of it is simple: Suzuki is focused on creating small, cost efficient vehicles, but the looming requirements of the future and the technological development required has left them a little worried that their products may not be up to scratch. On the other hand, Toyota has these various technologies in development and limited rollout, but they lack the ability to develop strategic partnerships with local companies in the way Suzuki has with Maruti and the like.
Both companies will continue to compete independently of each other, but they both have a lot to gain from a partnership like this. Suzuki could share a great deal of technology with Toyota and help their vehicles become more practical propositions without the penalty of research and development, while Toyota can capitalize on Suzuki's experience with alliance development. The two companies are still open to other companies joining in this collaboration.
For now, the collaboration is merely in its discussion phases, but with Toyota's desire to expand aggressively it may move towards something more solid in the next few months.