This is really the biggest thing I miss in making the switch over to the L900. My original Galaxy S (Captivate) had a dock - and it's usb port was on the "top" of the device. It laid on it's side and slid "left" into the charging port. I see no reason the same couldn't be done with the Lumia 900. The one downer is that, as it has been rightly mentioned, no auto-rotate. But I could deal with a hastily developed app that basically served as a clock/notification center that was oriented landscape...the real pain would be having to launch it every time you dock it (or undock it).
Now to go search for that Lego solution. Yes, I'm that desperate.