SuperPost By Myspace Post once, publish everywhere: available in the Iphone appstore
Myspace which is still the number 2 social network on mobiles just released an Iphone app called "Superpost"
From their website :
SuperPost By Myspace
Post once, publish everywhere
• SuperPost is the easiest and fastest way to update all your networks at once while on your iPhone.
• Share photos, videos and updates with friends on Myspace, Facebook, and Twitter.
• The simple and seamless flow makes updating super easy and super fast.
• Update your status and post photos, videos, or links.
• Preview photos and videos before sending.
• Upload HD video while on Wi-Fi.
• Pick and choose which services to publish to.
• Broadcast your updates in your Stream and on all your networks.
• View a history of all your updates posts sent using the app.
• Post updates even while using other apps (perfect for uploading videos!)