SEAPosting in Channels with Hash Tags
To put your post into a channel just leave the #tag in the text box when writing a message.
This let's us know where to show your message. Use more than one channel hash tag if you'd like.
You can use the same tags while posting on your MyStream page to put your post into the right channel.
More about Hash Tags...
The concept of tagging is nothing new to the internet community, but letting users organically organize content by placing keywords right into posts is fairly new to the social networking micro blogging world. These have been dubbed "hash tags" and often have the # symbol at the beginning. However, any site or network can make their own rules, or let them happen and listen to users.
A Little History
The # symbol notation is a carry over from IRC (a chat system) when a #chatroom convention was used to enter a space to talk :)