The main blog for thing-a-day is at thing-a-day.com.
Here is some practical and backgroundinformation.

1. What is this about?

Thing-a-day is a yearly creative sprint that is held every February and brings together hundreds of creative minds. The idea is simple: sign up is open to anyone and participants commit to create one new thing a day every day for the entire month and post it on the collective blog.

Participants can work in any medium and are free to follow-up on their commitment or not.

2. How do i signup?

Registration closes on Feb 1st at midnight!

Step 1: Create an account on Posterous.

Step 2: Fill out this form with a VALID posterous username (not your full url) and the same email you used to create your Poserous account.

Step 3: After a short while (not immediate) you will get a confirmation email saying you can now start posting on thing-a-day as an official contributor

Done! Get started!

3. How do i post?

Once you recieve your confirmation email, you can start posting by emailing your content to post@thing-a-day.posterous.com.

You can send pictures, videos, sounds and of course texts as part of your post by attaching them to your email. Your subject line will become the title of the post and the rest will automatically be formatted.

If you want to send your post to your own account as well (which is recommended so that people can follow you through the Posterous system), also send your post to your own post@youraccount.posterous.com address. Make sure you enter BOTH addresses in the TO field as it seems posterous sometimes ignores addresses in cc.

4. What should i post?

You can post anything in any media but remember this is an exercice in creativity, it's about the process of making stuff, not making finished impossible stuff. Your main challenge is to stick to it for all 28 days of February!

Pick a theme for the month or for the week, spend around 20 minutes a day on your piece and send it out!

Please don't post anything that doesn't belong to you or that most people would find offensive. We'll use our own judgement in case there is a problem. Please remember you're also under Posterous terms and services this year.

5. What if i want to follow people more closely?

Click on someone's name and access their own Posterous account. If they have been posting on this account as well, you'll be able to subscribe to thier feed this way.

6. My posts appear but they don't say who they are coming from?

The email address you are posting from is not associated with a proper Posterous account. Double check what name you've registered under and what email address and contact Posterous at help@posterous.com if you think there is a mistake somewhere.

7. So, What's with this year's edition?

This year, we decided to try moving Thing-a-day to posterous.com and take advantage of their simplified functionalities and services.

Feel free to browse through their http://posterous.com/faq/

8. How did all this start anyways?

Thing-a-day started in 2006 with support from Eyebeam center for Art and Technology and based on an idea by Ze Frank. Mouna Andraos with Mohit Santram maintain the site since then. Over the years, the site has had the support of numerous people including Jeff Gray, Steve Lambert, Michelle Kempner and many others.

9. What happened to the old archives?

We're hoping we can have them back online at some point in February. We still have them but we've had to move things around quite a bit to get settled in our new home.

10. Questions?

Try info [@] thing-a-day .com
We'll do our best to answer promptly.