I guess the first "instrument sample library" was assembled by Harry C.
The Vienna Symphonic Library (The Cube) will be available soon in 24
bit. The the full library will cost $11,000.
Not only does this library contain lots of orchestral instrument
voices, it also includes a variety of articulations (of each note of
each voice).
http://vsl.co.at/The demo mp3's are very good! (and probably midi sequencer triggered!)
Clay
p.s. A lot of current movie soundtracks have been produced using this
type of sample library.