Though the official press release seems to elude us, various reports indicate that Rome: Total War - Barbarian Invasion has shipped to stores, and Creative Assembly's RTS expansion should be available in both Europe and the U.S. (thanks Frans). Here's what looks to be the whole deal courtesy of Gaming Age:

SEGA Europe Ltd and SEGA of America Inc. today announced the availability of Rome: Total War - Barbarian Invasion, the widely anticipated PC CD-ROM expansion to the million-selling hit, Rome: Total War. From the creators of the award winning Total War franchise and recently acquired SEGA studio The Creative Assembly, Rome: Total War - Barbarian Invasion reflects 200 hundred years of change along with updated battle AI, and new maps and gameplay features.
Tear Rome apart by leading hordes of barbarians or stand and defend the Empire as a leader of one of the two former Romes, the Western and Eastern Empires. 200 years have now passed since the main campaign in Rome: Total War. The expansion offers RTS gamers 10 new factions and new gameplay features such as night battles, combat effects, and fighting styles. Players can now control vast armies and over 100 new units as they battle across an updated European map that now reflects the historical changes since Rome: Total War.

"Fans of Total War and RTS games can now defend or sack the Roman Empire with an unparalleled level of historical accuracy and gameplay options," said Scott A. Steinberg, Vice President of Marketing, SEGA of America, Inc. "SEGA is committed to maintaining the vitality of the Total War brand and will continue to support fans with great expansions and leading edge RTS content."

Rome: Total War - Barbarian Invasion commences just after the last Emperor of a unified Rome has died. His successors in Rome and Constantinople are now uneasy allies and rivals for power. The ‘barbarians' are massing along the borders, and in some cases are living inside what used to be Roman territory.