With 19 out of 21 votes, the overwhelming majority of voting members were in favour of the standard, but an email in Mozilla's ECMAScript discussion list said that those opposing the standard were the heavyweights IBM and Intel. IBM's reason for rejecting the proposal was content-related; it's unhappy with the lack of precision with decimals number handling. Intel, on the other hand, just didn't have enough time to check potential intellectual property implications.
Originally, version 3.1 was supposed to follow after version 3 of the standard. The members also discussed a version 4 at some point, but couldn't reach an agreement on it. This version would have contained such features as the namespaces that Adobe implemented for ActionScript. Those features are are not part of the newly approved version.