1. Laser Interferometer Space Antenna
2. Terrestrial Planet Finder
3. James Webb Space Telescope
4. Overwhelmingly Large Telescope
5. The Square Kilometer Array
6. European Extremely Large Telescope
7. Large Synoptic Survey Telescope
8. Thirty Meter Telescope
9. Giant Magellan Telescope
10. Atacma Large Submillimeter Array
The future of great astronomical observatoriesThis list is merely my musings on astronomical observatories. There are more productive observatories that have already built, or will be built, but these are the most exciting in my humble opinion. This list does not include even more speculative projects such as plans for a lunar radio telescope or an extremely sensitive and larger LISA. There are other planned observatories not mentioned, like IXO, that just didn't make the list.
It is of note that there is an over arching principle of segmentation present in all of these observatories; these telescopes use multiple almost identical components working in unison in order to gather signal. LISA, the SKA, TPF, and ALMA use interferometry or correlation to observe. The EELT, TMT, JWST, use segmented primary mirrors. GMT uses several identical mirrors to simulate one primary mirror. LSST uses a massive array of CCD detectors. Modern technology and the economic/complexity benefits of reproducible industrial construction make this possible, but it takes modern computing to gather the data from the individual receiving elements and produce coherent observations and science.