Within the coalition, the Moderates, the largest party, was the clear winner, at 30% of the vote, with a 4% point improvement on the last election, and just one percentage point away from becoming the largest party in Sweden. It's much smaller partners all lost support, perhaps illustrating the perils of being the small partner in a political coalition. The largest party has most of the power, but all parties equally share the responsibility and blame. I don't doubt the coalition will hold up this period too, but I'd expect to see less discipline and more public disagreement as each small member will try to make their mark in preparation for the next election in turn.
The Social Democrats got 31% of the vote. This is quite a disaster. To put it in perspective, this is a party that's long used to rule the country all by itself, and when the got 36% in the last election it was bad enough that then leader and Prime minister Göran Persson resigned during the election night. Losing another 5%-points from that historical low is bad enough that I doubt current leader Mona Sahlin will get another chance.
Why did they do so badly? One reason is the Moderates. They've successfully transformed from a low-taxes-and-a-strong-army conservative party to a centrist general party that have taken over many of the political issues long held by the Social Democrats. When your opponent agrees with you, and even proposes legislation in line with your own older party programs, it's hard to mount an effective campaign.
Another reason is their coalition. Unlike the current center-right coalition, none of the opposition parties have had any history of formally working together. For most of their existence, the Social Democrats and the Communists have been bitter rivals (Sahlin at first tried to exclude the Communists, but was overridden by her own party), and the Green party doesn't really fit in with the other two on the left-right scale. In fact, the Greens and the Communists probably disagree on as many of their important issues (such as conditions for small businesses) as they agree on. The coalition never really looked like anything more than a tactical riposte to the government coalition, and the need for it exposed just how weak the Social Democrats have become.
The rise of racist neo-Nazi Sweden Democrats is the most distressing result. They have certainly taken voters (mostly young, male and poor) from most parties, but it seems the Social Democrats and the Moderates was harder hit than others. The Moderates have moved from the right and towards the center for the past two election cycles so I guess it's only natural some of those on the militaristic right2 no longer felt at home. Some have moved to the People's Party, which has moved to the right, but others no doubt felt more at home with open racism.
There is a streak of xenophobia in the Social Democratic party and their union movement too; while the leadership is quite internationalist, the rank and file keeps its solidarity firmly within Swedens borders. There have been more than a few incidents where union officials have harassed and verbally abused workers from other EU countries quite legally working in Sweden. The Sweden democrats seem to have been able to tap into this ugly vein within the party.
The post-election political dance is in full swing. It's quite clear that the coalition will form a new government - technically the speaker of the house decides who gets the first shot at it - but exactly how is still an open question. The Greens are refusing any idea of cooperation with the coalition, though that may well be a negotiation tactic. At the same time the coalition is strong enough - just a few seats short - that they can form a strong minority government even without a formal deal with another party.
As for the Pirate Party, they did not get a seat, and did not get close. The surprise gain of two seats in the European parliament notwithstanding you can't really build electoral success overnight. It's back to the grind for them, to build a stable cadre of supporters locally and regionally, then try again the next election or the one after that. There are no easy shortcuts to be had.
#1 The last batch of mail-in and foreign votes are still being counted so final results aren't in until Wednesday. However, these late votes aren't that many and don't normally differ that significantly from the general results, so while they could conceivably switch a marginal seat from one party to another, they will not affect the overall outcome.
#2 Anecdote is not data, and I certainly don't have any real statistics for this, so take it as a simple observation: when I was in the military service around 1990, a surprisingly and distressingly large number of the younger officers at our regiment had newsletters, music CD's and imagery connected with the Swedish White Power and neo-Nazi movements. And the Moderate party - supporting of military traditions, the nobility and royal house, and pro-militaristic stance - was by far the most popular among them.