The icefaces3-portlet Selenium tests were failing because the partial submit for ace:dateTimeEntry because the ace:ajax component tag was missing execute="@this" which was causing partial processing to include validation of all the fields. Since the firstName field is required, it was failing validation when partial processing was occurring for other fields.
The VDLDocs seem to point the "execute" docs back over to f:ajax's "execute" attribute:
So I think that would imply that the default should be @this but the observed behavior is @form. The workaround for this would be to add execute="@this" for each occurrence of ace:ajax.