If you haven't noticed by now, Windows Live signin pages, powered by Live ID, have improved their muliple account support, now feature profile pictures as well as reordering accounts by most recently used. For those who use several accounts on one PC this is a welcome step forward, especially when compared to the legacy Passport signin pages that still exist on non Windows Live sites (e.g. microsoft.com). Unfortunately multiple account support across other Windows Live services is still lacking, especially with regards to the big three of Mail, Messenger and Spaces.
For those developers interested in using Windows Live ID, fear not; we should start seeing some documentation for that coming soon.