tweet is a command line program for posting to Twitter.
To install:
$ go get github.com/pteichman/tweet
To use:
$ tweet -c creds.conf "Had pancakes for breakfast #winning"
The config file contains your Twitter credentials. It's up to you to go through the OAuth dance to get them. It looks like:
{
"ConsumerKey": "....",
"ConsumerSecret": "....",
"AccessKey": "....",
"AccessSecret": "...."
}