It seems like there's a few people who'd be interested in this. Hmm...perhaps I need to dig out the source again, dust it off and get to work. My current source is not available publicly as it is *extremely* in development and at the moment really only shows alarm and permissions windows, allows you to create and delete virtual machines and does some multi-threading to check for status updates to alarms, inventory window etc in the background.
In answer to one of the questions, yes, it is mainly backwards compatible in current form with ESXi and ESX 4.0. The API did not change much between these versions. I have not tested it against ESX 3.5 and earlier versions because by the time I started working on this 3.5 was already nearing EOL.