It sounds quite nature to have the table of content and legend list together, just the way in ArcMap and web ADF. However it's quite strange that the JS API kind of choose to separate them, even in the new arcgis.com and the brand new v2.1 armed with legend service in ArcGIS 10 SP1. Switch back and forth is unnecessary. Older version needs some SOAP call, and the API even has code to handle some simple symbols that do not come as a bitmap. Yes, it can be done externally, but since the API already providing a legend widget, it will be nice to have it come the the API?