There have been a number of updates to Windows Live Spaces over the past few months that have moved to emphasize using the site to communicate and connect with people as opposed to personal publishing. When Windows Live Spaces was launched about three years ago, it's sweet spot was as a way for users to publish blog posts, photos, lists of their favorite music or books and other forms of personal expression. Over the past few years, experience has thought us as an industry that providing a platform for our users to communicate and connect with each other is more valuable to them than simply providing a personal publishing platform. With that in mind, the product team has been working at a rapid clip to add more features to the site that enable people to connect and communicate with each other.

From the blog post entitled Stay in touch with friends and meet new people with Guestbook and Messaging on Spaces on the Windows Live Spaces team blog we learn

Spaces has always been a great place to express yourself and share the stuff you care about with your friends or the world at large, but there haven’t been that many options to communicate with people through your space. There are lots of ways to passively connect you’re your friends –Windows Live Messenger gleam integration, the Friends feature, and the What’s New feature which has now been incorporated into the Spaces Home, but in this release we really focused on giving you active ways to communicate with your friends and the people who visit your space through our new Guestbook and Messaging features. We know you’ve been asking for these features for a long time (particularly the Guestbook!), and we’re glad that we can finally deliver them
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Guestbook
The Guestbook is a brand new module that you can add to your Space through the Customize menu or by clicking the “+” sign on a Guestbook in someone else’s space...Once you add the Guestbook module to your space (new spaces have it by default) you can add a custom greeting, which can include formatting, images, and even videos:..Visitors to your space can then leave and view comments in your guestbook (they can use images, video, and formatting too):
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Messaging
Where the Guestbook is a great place for public communication the new Messaging feature is a great way to meet people on spaces or use it to stay in touch with your Spaces Friends. With Spaces messaging you can send private messages to your spaces friends or other spaces users without revealing you email address to others or having to using an outside e-mail service...You can access your messaging inbox from the Spaces Home by clicking on the “Messages” link:

On your messages page you can view and delete messages you’ve received and sent, and you can reply to these messages:

There are lots of ways you can initiate a new conversation through Spaces messaging. If you are visiting a cool space you can click send a message from the visitor tools on that person’s space:

You can also click the “Send a message” link at the bottom of a blog post to send that person a message referring to the post:

That was from two months ago. Last week there were fresh updates to the service which was announced in the post entitled Just released: Three months of new updates to Windows Live Spaces that stated

As of this evening, we finished rolling out the latest version of Spaces. Whether you or your friends are checking out what your Messenger contacts have been up to, organizing your lists, navigating around your space, or setting up a space, the latest Spaces release has a lot of new features.
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Spaces home page updates 
We've made some slight changes to the design of your Spaces home page so it's even easier to see what your Messenger contacts are doing with their spaces.   We've also added birthday reminders!

To see birthday notifications, first share your contact information and then subscribe to a contact's information.  You can subscribe to contact information through Spaces, Messenger, or Hotmail.

• Spaces:  Roll over a person's profile picture and in the preview window, click on the “Receive contact updates” link
• Messenger:  Right-click a contact, click “Edit contact”, and check “Subscribe to updates for this contact”
• Hotmail:  Click Contacts in the lower lefthand corner, “Edit contact”, and check “Receive contact updates from this person”

If your contacts have entered their birthday information, you'll see their upcoming birthdays on your Spaces home-page, and you'll be able to send them an electronic greeting card from MSN Greetings powered by American Greetings  (currently only available in the US market).