No, Twitter isn't raising the number of characters you can use in your Tweets beyond the 140 you have always been able to use...but in some cases, you'll be able to Tweet a little longer.
Until now, if you're replying to someone or a group, tagging tall those other usernames would eat up your 140 characters...but not anymore!
Last year, Twitter made sure the links for photos, videos, quote Tweets and polls would no longer count toward your character count.