Mellotronists

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.