Both mobile apps:
1. profile editing
2. easier way to author content
3. subtle notice when there's new stuff to read
4. subscribe to notifications from circles
5. support for communities
Android:
6. full-size backups of your photos
7. photo spheres in the stream
8. share your mood with others
9. animated GIF support
10. birthday reminders in Google Now
11. lock screen widget
iOS:
12. swipe through photo albums inline
13. tap once to view photos in all their glory
14. subtle pan-zoom-scale effect applied to stream photos
15. longer post snippets
16. bigger post photos
17. comments that slide in underneath each post
Events:
18. send messages to specific guests
19. event creators can see who's opened their invite
20. invite people by just pasting event URL in email/IM
21. RSVP with number of guests you're bringing
22. duplicate an event
Hangouts:
23. ultra low bandwidth mode
24. improved single-person broadcasts
(source: https://plus.google.com/103541694080221120019/posts/Xt7YWmuf...)
Both mobile apps:
1. profile editing
2. easier way to author content
3. subtle notice when there's new stuff to read
4. subscribe to notifications from circles
5. support for communities
Android:
6. full-size backups of your photos
7. photo spheres in the stream
8. share your mood with others
9. animated GIF support
10. birthday reminders in Google Now
11. lock screen widget
iOS:
12. swipe through photo albums inline
13. tap once to view photos in all their glory
14. subtle pan-zoom-scale effect applied to stream photos
15. longer post snippets
16. bigger post photos
17. comments that slide in underneath each post
Events:
18. send messages to specific guests
19. event creators can see who's opened their invite
20. invite people by just pasting event URL in email/IM
21. RSVP with number of guests you're bringing
22. duplicate an event
Hangouts:
23. ultra low bandwidth mode
24. improved single-person broadcasts
(source: https://plus.google.com/103541694080221120019/posts/Xt7YWmuf...)