I can also suggest using the Tweet module. Here is a quote about it (from the module's project page):
... provides links to post pages to Twitter in a new window or tab. The tweet will be in focus and will contain customizable text that can hold the relevant URL, title and anything else you need it to (like hashtags). The URL can be automatically abbreviated at the administrator's choice of service by integration with the Shorten URLs module by the same author.
When Twitter is opened, if the user is not already logged in, Twitter will prompt them to log in, and after logging in will redirect users to the tweet form as described above.