The e-doors are open. Apple has just launched an online store full of digital iBooks made for use on the iPad. Users can browse, preview, and download a wide variety of books, but only iPad users will be able to use iBooks. A complimentary digital version of A.A. Milne’s Winnie the Pooh is being offered to celebrate the grand opening. Watch your back Amazon.

This past week iTunes reached a significant milestone: over ten billion songs downloaded. Started in 2003, this amazing amount of downloads pays tribute to not only a significant amount of revenue, but also to Apple’s extremely powerful presence in the music industry.

All-time-most-downloaded song? The hip hop group Black Eyed Peas take top honors with “I Gotta Feeling”. Their “Boom Boom Pow” is the third.

Most songs in the top 25 most downloaded? Lady Gaga with three singles: “Poker Face,” “Just Dance,” and “Bad Romance.”

Other artists in the top 10 include Jason Mraz, Flo Rida, Taylor Swift, Leona Lewis, and Ke$ha.

Who won iTunes’ contest to be the 10 Billionth person to download? Louie Sulcer of Woodstock, Ga. Sulcer purchased Johnny Cash’s “Guess Things Happen That Way,” and as a reward for downloading the 10 billionth song from iTunes, was given an iTunes gift certificate worth $10,000.

Just as significantly, iPhone apps are making their mark. Last week they passed the 3 billion mark. Pretty amazing given their relatively young existence.