It's not a totally new concept: Twitter has been testing this interface for months and new accounts were already seeing it, along with selected groups of users. Seemingly content with how those trials went, Twitter has now deployed these features across all Twitter accounts.
The update adds two major features: search and Twitter trends. Both are smart additions: search is a vital part of Twitter that until now required typing "search.twitter.com" in your browser. You can now save those searches, too. Trends, meanwhile, fosters more engagement by showing you what everyone else is talking about.
Twitter is famously shy of adding new features, believing simplicity is the route to success. With essentials like search and trends now present, might they eventually add retweeting to the interface, as a new petition at Retweet.com is demanding?