Suppose there is a war, and nobody came to tweet about it. The two enterprise social software vendors Yammer and Chatter are currently at war for market domination, and copycatting their way through it.

If the internet is made for cats, then even more for copycats. There is a war going on between two cats in Enterprise social software. Their promise is "bringing together all of a company’s employees inside a private and secure enterprise social network" according to Yammer. Or to "connect with your coworkers to work together and be more productive" according to Chatter. Anyway, both companies look astonishingly same.

VS

Spot the difference? Comment on the group if you can find them.

What makes the battle even better: they quickly try out different designs every day. You never get the same page twice! So, see it as a game:

• collect them all! (collect images of the landing pages, here)
• spot the difference! (between yammer and chatter, but also between different views
• spot the change! (what has happened?)
• spot the uniqueness! (what is typically yammer/chatter?)
• guess whats next!

...endless possibilities for spectators...

To play along, collect your images and comments here: http://www.flickr.com/groups/yammerchatter/

Note that Yammer was first and therefore Chatter is proably the copycat. But now, its hard to tell. Here is a great video by Yammer to get you started:
http://youtu.be/MuSLk5FkNrs