There seems to be a dearth of Atmel AVR™ ATMega328 chips in the UK at the moment. with Farnell and RS Components both awaiting deliveries. I needed ten urgently, and found them at Rapid Electronics.
These are unprogrammed chips without a bootloader. If you want to use them in Arduino™ clones you will need to burn in a bootloader yourself.
I've been doing just that, using phenoptix' AVRISP board with an Adruino UNO.
I'll blog about that tomorrow.