SmartGWT provides an alternative to UIBinder called Component XML that also works with SmartGWT Visual Builder.

http://stackoverflow.com/questions/2940113/smartgwt-ui-definition-using-xml

There is a Google Code project for adding UIBinder support to SmartGWT:

http://code.google.com/p/uibinding-smartgwt/

Official support is waiting on Google to add some flexibility to the UIBinder mechanism (custom parsers). At that point we plan to support UIBinder with the same (or nearly the same) syntax used for Component XML.