Twitter recently made a change where you will not see any tweets from folks you follow if they start with a @username that you are also not following.
This means that if you start a tweet with @username, only your followers that are also following @username will see it the tweet.
Personally, I like the feature. But some folks don’t. So here’s how you can easily get around it:
When replying to someone, don’t start your tweet with @username.
What I typically have always done when replying to other tweets is:
1. retweet, …

Microsoft soon to come out with Wii competition. finally! http://bit.ly/13yFz7

SECURITY ALERT: User Powerpoint? Get the MS security patch. Big hole discovered. Mac too. http://bit.ly/6oow7

Better think twice before you refer to Wikipedia; what happened to journalists who didn’t: http://bit.ly/G836S

Why Bit.ly is hot. HT: @howardlindzon http://bit.ly/jR42z