In 2004, UCLA mathematics professor Terence Tao, along with Ben Green, a mathematician now at the University of Cambridge in England, solved a problem related to the Twin Prime Conjecture by looking at prime number progressions — series of numbers equally spaced. (For example, 3, 7 and 11 constitute a progression of prime numbers with a spacing of 4; the next number in the sequence, 15, is not prime.) Professors Tao and Green proved that it is always possible to find, somewhere in the infinity of integers, a progression of any length of equally spaced prime numbers.

Note: If you cannot access the article on the New York Times site, try this site:
http://www.iht.com/articles/2007/03/13/healthscience/web-0313math.php.