Publishers:

• Amazon signs up authors, writing publishers out of deal.

Mobile Computing:

• Cellphone users will be warned before hitting plan limits.

• Google's Honeycomb offensive musters just 3.4m tablets.

• Apple's success is also Google's gain as mobile advertising balloons.

• iPhone 4S first weekend sales top four million.

• Inappropriate content making its way to mobile apps for children.

• Amazon in iPad challenge narrows margins.

• RIM offers free apps to appease BlackBerry customers.

Social Media:

• Are Facebook ID cards in our future?

• Facebook invests a lot in business equipment.

Pearls of Wisdom:

• YouTube's own marketing advice for retailers: create content, not commercials.