http://www.airbus.com/dynamic/media/press_releases.asp

SilkAir, the regional wing of Singapore Airlines serving 25 Asian destiations, ordered 2 A319 and 4 A320 for network expansion. It is operating 4 A319 and 5 A320, with 1 A320 ordered eariler to be delivered in 2003.

Easyjet just signed contract for 120 A319, making it the 1st European low cost carrier to operate A320 family. Stelios Haji-Joannou, easyJet Chairman, said sticking to old-fashioned fads like "low cost airlines only fly Boeing" does not reduce costs, because of lack of commonality among B737 family (that's why SAS ordered A321 instead of B737-900 even it operates many B737-600/-700/-800.)

The chairman said the advantage of wider cabin of A320, so aisles can be made wider and hence faster passenger flow. He also said he is satisfied with sizing of A320 family, with A321 being to seat 220 seats in Easyjet's 29" seat pitch layout, larger than B737-900.

But I don't think the sizing of A320 family is very good, as A321 is much larger than A320 (150 vs 185 in typical 2-class layout), thus leaving a large gap between them. Boeing B737NG, on the other hand, have more even difference in capacity of no more than 24 between any 2 members.