Over the last few months there have been some small incremental improvements around MSNs Mobile portal to tweak it for small screen devices, but this week they've all come together with a roll out of the new polished platform (for the US market at least - the worldwide rollout continues).
The workflow has been heavily optimized to give you access to information such as news, weather, stocks and TV listings with the minimal number of clicks from the homepage. Email and messenger integration is improved and, of course, search is easily accessible.
One really cool things is that the new MSN platform detects the handset and optimizes the site for that device, adjusting things like font sizes for different screens - it's little touches like that which make the portal easy to use
If you have a Windows Mobile or J2ME equipped phone don't forget to check out Windows Live Search for Mobile as well for a more integrated search, mapping and traffic interface right from your phone (including GPS integration).