A new rail link to connect Stockholm and Oslo opens in August, cutting the time from 6 to 4-1/2 hours. It's aimed at international professionals who might otherwise have chosen to fly between Scandinavian capitals.
It almost got delayed; Norway last week put a 2-1/2 year hold on the completed project to upgrade overhead power lines along the way; in response to requests from Sweden, that work's been postponed. The new service is operated by SJ, the Swedish national rail operator, but makes part of its run on Norwegian rails.
More details HERE