Updated for me in Canada when before it said it wasn't available in my Country.
@borjaox: This is what I did,
1. Went to https://market.android.com/details?i...oid.apps.books
2. Click Install
3. Signed in and selected my phone - It said it was compatible and it would send the update over shortly
4. Opened Android Market
5. 2 updates were available (Google Books and another app)
6. Clicked Update on the My Apps screen to download both at once
So that's how I got it, not sure if it was able to download it cause of the Update All or cause I pushed it to my phone.
Give it a try