... and where does that name come from?
The name "Talea" is an homage to the late French composer Gérard Grisey, who wrote in 1986 a muiscal work for five instruments named Talea. More on Grisey here: last.fm and here: ircam (in French). Here is an interview with the composer, from 1996.
Originally, the talea is part of a compositional technique dating back to the Middle Ages. It has received several slightly different definitions over its history; here is the oldest one (ca.1340), which happens to be one that is still most commonly accepted today, quoted in the Grove Dictionary:
A configuration of pitches and its repetitions are called “color”; a rhythmic configuration and its repetitions are called “talea”
(Grove Dictionary of Music and Musicians, 2001 Edition)
So a talea consists in a rhythmic pattern which is repeated again and again throughout the piece. The interesting trick is that composers usually combined this rhythmic pattern (the "talea") to a sequence of pitches (the "color") which had more or fewer notes than the rhythmic pattern.
For example, here is a rhythmic pattern of 5 values:
and a pattern of 4 pitches:
When combined together and repeated, the two patterns remain out of sync for 5 x 4 cycles. The pitch sequence comes back in phase with the rhythmic one every 20 notes:
This technique has found favor again in more recent times: in the first movement of the Quartet for the End of Time by the French composer Olivier Messiaen (written in 1940), for example, one can find a pattern of 17 rhythmic values combined with a pattern of 29 different chords.