Two analysts comment on the bombing, without assigning blame: Starts
The targeting of Norway should not be a surprise. In 2003, Al Qaeda --- through its current leader, Ayman Al-Zawahiri --- first threatened Norway, possibly because of the involvement of Norwegian special forces in Afghanistan. Since then, the Norwegian role in Afghanistan has expanded, although its troops are to be withdrawn later this year.
Ends:
Whatever the cause of the explosion, the attack will have widespread ramifications in terms of Norway’s security policies, domestic politics, and in relation to broader European security issues. If Al Qaeda is shown to have some connection to the attack, or even it claims a connection, it will represent at least a small resurgence of the organization under its new leader and potentially a shift to attack more “soft target” countries that are less protected than high profile targets such as the United Kingdom and the United States.
Link:http://www.enduringamerica.com/home/...-al-qaeda.html

In a comment, so not verified by research:
On German TV a terrorism expert pointed at an explosion at the Saudi Embassy in Oslo last year, to Norway's participation in the forces fighting against Qaddafi, and to the fact that one of the attacked buildings is Norway's Oil Ministry.
That link refers to a SAAG analysis, a year ago:http://www.southasiaanalysis.org/%5C...paper3915.html

A different angle, Norway & CT:
Norway’s intelligence service had previously been criticised for its failure to keep track of suspected terror cells and the country was felt to be complacent about the prospect of a terror attack, secret cables from the WikiLeaks files reveal.
Link:http://www.telegraph.co.uk/news/worl...or-attack.html