Twitter rolls out a bunch of changes:
1. Allow any follower to DM (direct message) you
2. More visual tweets in the feed (vine!)
3. Advertisements
4. Alerts for emergencies (not so new)
5. Recommendation service (not so terribly new; @magicrecs)
6. Twitter apps updates (droid tablets (yay!); IOS)
7. Watch TV from tweets
8. Scheduled tweets

More here:
Good overview of 7 features (there are more): http://www.fastcompany.com/3020772/work-smart/7-big-recent-twitter-changes-you-should-know-about-before-the-ipo

More about how it will look:
http://techland.time.com/2013/10/30/twitters-design-changes-arent-all-terrible/

Emergency alerts:
http://mashable.com/2013/09/25/twitter-alert-system/

Scheduled tweets:
https://blog.twitter.com/2013/now-available-scheduled-tweets

Recommendation service:
https://blog.twitter.com/2013/stay-in-the-know

Watch TV from Twitter
https://blog.twitter.com/2013/change-the-channel-directly-from-twitter