The new MSN Toolbar beta is live. If you want to signup to use the beta, you can now do so on Microsoft Connect (places are limited so register asap).
While Silverlight is powering some nice popups to show the MSN content, reactions we've heard so far have been mixed. The biggest question by far is whether this means Windows Live Toolbar is being retired? We've heard that Windows Live Toolbar is still under development for Wave 3, so hopefully no worries there.
The difference between the two toolbars is much the same as the general difference between the two brands; MSN provides pre-selected content access, whereas Windows Live provides access to the information and services you care about. Looking at it this way, having two toolbars make some sense (admittedly I'm not fully convinced).
Microsoft, Beta, MSN, Silverlight, Toolbar