The Pirates have 13 per cent of support nationwide, making them the country's third most popular party after Chancellor Angela Merkel's Christian Democratic Union (CDU) and the opposition Social Democrats, survey firm Forsa said last week.
Trailing the Pirates are the Greens, a far-left party called the Left and the pro-business Free Democratic Party (FDP), the Christian Democrats' coalition partner, which seems to be falling apart.
"The children of Marx and Microsoft" is how the centrist daily, the Sueddeutsche Zeitung, described the populist promoters of libertarianism and cyber-savviness. "The Pirate Party is no longer just a party for net-nerds in hoodies but represents demands from across society."
The renegades are also looking beyond the national horizon. Pirate Parties in more than 20 countries, meeting at the weekend in Prague, discussed setting up a European-wide party and jointly contesting the 2014 elections to the European Parliament, where there are already two Swedish Pirate MPs.
In a clear sign of concern, the big parties are opening up Twitter accounts and papering their Facebook "walls" - but their cyber skills have had varying degrees of success.
In the western city of Duesseldorf, CDU members bought internet domain names with the word "pirate" in an attempt to subvert the newcomers' campaign for the election in North Rhine-Westphalia. Users who clicked on the site were redirected to a CDU website. But Pirates supporters hacked into the CDU site, leaving a message that read "Help - I'm being held captive on a Christian Democrat website".
Stunts like this have helped propel the Pirates to rebel status. "The Greens had this role for a long time, but now their leaders are in their 50s, and it is a very mainstream party," observed Manfred Guellner of Forsa.
But what about substance?
That's something the fledgling party itself admits is a work in progress. It is pushing hard on digital issues such as opposing a global anti-piracy pact, scrapping copyright restrictions on music, films and writing (and causing an outcry among some artists) and on removing patent protection on pharmaceuticals.
It wants to create grassroots democracy through the internet and encourage transparency by placing the details of public-sector contracts on the internet.
As, in its view, full unemployment is impossible, there should be a "basic unconditional income" for all. It supports Germany's withdrawal from nuclear energy and wants public transport to be free for environmental reasons. It wants drugs to be legalised.
Whether the Pirates are able to put flesh on these bones is a pressing question. Another challenge for the party is to develop a structure - it has an unfocused, anarchic debating style reflected in bouts of internecine sniping on Twitter.
Right now, the traditional parties are rattled but draw comfort from the belief the wind will spill from the Pirates' sails well before the 2013 federal elections.
"The Pirates will lose their charm when they have to set out concrete proposals in the coming months," Greens leader Cem Oezdemir told the newsweekly Focus at the weekend. "It's not enough to demand education for all or free public transport if you don't also say how you are going to carry it out at a time when money is tight."
