The first time I’ve seen something called a Twitter Alert:
It was just dumped into my stream, hours ago, to scroll by like any other tweet.
On Weibo, there’s a fixed area where they put a dismissable ad.
Twitter should steal that idea for Twitter Alerts. An Alert is something important and shouldn’t just scroll by in a timeline. It should be there at the top where people see it first and can click to dismiss it after reading.