I have to somewhat disagree here. I see no reason to have a Do plugin
that simply opens the search 'in the browser'.
I think the OpenSearch plugin should suffice for this type of action:
http://do.davebsd.com/wiki/OpenSearch_Plugin
And then find the search plugin here:
http://mycroft.mozdev.org/search-engines.html?name=wolfram&opensearch=yes
- Robert