Highlights:

• Introducing Photo Filters
• Keep up with key people using Inner Circle
• Facebook News Feed and cross-posting
• Update GTalk status
• Conversation thread view
• Manage multiple accounts
• Tweet over 140 characters
• New color themes
• All new sound effects

Features:

• Tweet/ReTweet, Direct Mentions, @Replies, @Mentions, Trending Topics, Twitter Lists
• Photo and video support (multiple providers)
• Customized notifications
• Save and restore Tweet drafts in compose mode
• Edit profile
• Pull to refresh
• Tweets near you
• Location services including tagging and search
• Protected Tweet mode for privacy
• Recommended Users
• Saved searches
• Advanced Search functionality
• Mute capability – mute user for selected period
• Home Timeline – combines Tweets, DMs, @Mentions, etc.