Recently it has been revealed that VMware Converter 4.0.1 includes a web interface that is currently hidden.
VMware converter utilises a web service to interact with ESX hosts and it would seem that VMware are developing a web based GUI to wrap around it.
At the moment the product only exposes a login form if you connect to the address:https://ipaddress/converter/
There are several other functions partially implemented, like for example the file upload facility that is handled by the FileInput.js component.
It is currently unknown if VMware will be finishing this front end off but looks interesting.