If you love using Twitter’s free and handy service– which allows users to send “updates” (text-based posts, up to 140 characters long) via SMS, instant messaging, email, the Twitter website, or an application such as Twitterrific–you will like Twittercal. With Twittercal, you can add events from your Google Calendar to your Twitter account, so you can easily contact people about upcoming events such as meetings or social gatherings, and vice-versa: add events from your Twitter friends.
To join, you just request authorization and once Twittercal admits you, you add them as your friend in your Twitter account.
Twittercal.com In Their Own Words
“It’s a free service that connects your Twitter account to your Google Calendar. Add events in a snap from your favorite Twitter client. Follow the 5 steps procedure to get started.”
Why Twittercal.com It Might Be A Killer
Twitter is a great service and linking it to Google’s applications is a smart idea with a lot of potential. Twitter seems to be growing in popularity, so Twittercal is catching the wave.
Some Questions About Twittercal.com
Does the service allow you to create invites to events? 
