From the MSN Spaces homepage:
Windows Live Spaces – the future of MSN Spaces In the summer of 2006, we will unveil a more powerful version of MSN Spaces which will be called Windows Live Spaces! Stay tuned!
Nothing new to learn here if you listened to Harrison's interview with Mike Torres after the 10.5 update. What I find interesting though is that they chose to display this on the Spaces homepage several months in advance. An attempt to get users familiar with the Windows Live branding that will emerge publicly in April perhaps?
(Thanks Scott for the tip.)