Lots of bank, tax and insurance related stuff in Sweden these days switch to using BankID for secure logins on web sites. They ditched the java applet a while ago and switched to a browser plugin and native application instead, which then suddenly made them forced to write platform-specific code to achieve the same magic. More here
And not too surprisingly, the Linux version was poorly made and is not supported and is left with a really complicated way to install it which no doubt will prevent every Linux-newbie out there from using BankID on Linux. Annoying and rude if you ask me.