Social Media:

• Twitter tells advertisers to dig deeper: "Promoted Trends" get a price hike.

• Twitter stops whitelisting applications.

Ad Technologies:

• Forrester: Advertisers to double real-time bidding spend in 2011.

Mobile Marketing:

• RIM’s Playbook will get Android apps support.

• PayPal's micropayment solution opens to the public.

• Mobile Payments: the next battleground for Google, Apple.

Mobile Computing:

• What the Nokia-Microsoft deal means to Microsoft developers.

• Nokia-Microsoft: Will they succeed or continue to limp along in smartphones?

• Verizon iPhone 4 launch day a dud due to pre-orders, analyst says.

• Apple is said to work on cheaper, smaller iPhones.

Productivity:

• Sparrow, the beautiful Mac email client flies into the Mac app store — and into funding.

Legal/Regulatory:

• Nielsen backs Ad-ID standard for tracking digital ads.