The ratings are different today, hence a different rating for Lost and Alias and everything else for that matter.
Here are the ratings
AI - 27.1M
Lost - 14.2 Million - series low.
Invasion - Finale - 8.3 Million
Alias - 5.5 Million

, Down from last episode but up from the one before it
Americas Next Top Model - Finale - 5.7 Million
a UPN reality show beat Alias. Jesus. Who thought this could happen ever, and to the best creative sprint the shows had pretty much ever as well

Damn you ABC! I hope you die in your own septic tanks.
By moving LOST against AI and then Alias to Thursdays and giving Invasion essentially the best spot of the night, ABC have slowly killed wednesday.
Alias could take AI, It provided better ratings than Invasion in the versus AI timeslot. They had a good thing with their JJ Abrams block, god knows why they changed it.