It means you have over 3,000 posts. Here's the list or hierarchy:
Newly Joined - 0
New Member - 1 post
Junior Member - 10 posts
Member - 25
Veteran Member - 500
Grand Member - 750
Poohbah - 1000
Grand Poohbah - 1500
Magnate - 2000
Grand Magnate - 3000
Elder - 5000
Wise Elder - 7500
Legendary - 10000
Legendary Wise Elder - 20000
Wisest Elder Ever - 50000