Here's a legend for the new software images that you see around the forum:
New Forum topic - unread
New Forum topic - read
New single topic - unread
Announcement - unread
Sticky - unread
Topic - unread (locked)
Announcement - unread (locked)
Sticky - unread (locked)
Topic - read
Announcement - read
Sticky- read
Topic - read (locked)
Announcement - read (locked)
Sticky - read (locked)
New Topic - unread (you've posted in)
Announcement - unread (you've posted in)
Sticky - unread (you've posted [...]