We describe how the Virtual Observatory (VO) projects in Europe, the USA, Japan, and elsewhere are meeting the challenge of providing simple and efficient access to the data from the world's observational facilities, together with applications and computational resources required to support the analysis of this data. We note the pan-European Euro-VO project and its technological development VO-TECH project which are now in the process of designing the framework for comprehensive access to emerging high data volume facilities such as ESO's VISTA infrared survey telescope.

Science drivers from major new astronomical missions are helping to define the development of the VO. Scientifically this is in terms of developing systems able to meet the demands of the main science programmes shaping the ELTs. VOs must be able to handle the large data streams from the complex multiplexed instruments on the ELTs, and provide access to applications required to analyse/interpret the data. VOs must enable the effective distribution of ELT data to the global community.

Conversely, the rapid development of the Virtual Observatory, offers opportunities for major new projects such at the ELTs. This could be: in the design of their down stream data-flow systems; in terms of opening up access to ‘real-time’ availability of ancillary data flows; in multi-wavelength observational programmes.

We highlight these areas, and give some specific current examples of early VO usage in delivering science from, e.g. the mining of deep multi-wavelength surveys to study the high redshift universe.