I don't know what kind of criteria we need to hit to call the official start of an App Store price war, but quite a few companies have taken EA's lead from last week and dropped their app prices down in an attempt to get them on the top app charts before this week's store freeze by Apple. Pocket Gamer has a pretty good list of sales going -- most Namco apps are on sale, along with the Pac Man titles and Bit Trip Beat. Halfbrick Studios has also dropped prices on their games, bringing Age of Zombies and Fruit Ninja down to just 99 cents and adding new content to both. Samurai II: Vengeance was also dropped to 99 cents, as we tweeted on @TUAW earlier today.
A number of apps are trying to compete by adding features -- Touch Arcade has a good list of those, including Imangi's Max Adventure and Capcom's Arcade title as well as Sega's Chu Chu Rocket.
The weekend hasn't changed EA's grip on the App Store charts -- 6 of the top 10 are still EA's titles, and Apple is actually running banners on the App Store advertising EA's big sale (which has some smaller developers a little miffed). We'll have to see what happens as the week goes on. The store freeze is set to go down on Thursday through Tuesday, December 28, so any apps in the charts then will stay there over the holiday weekend.