Since the sibling comments already explained the Finland-Swedes, I'll just add a bit of trivia relevant to this crowd: Linus Torvalds is one of them. His first language was Swedish, and apparently he's never spoken Finnish particularly well.
He speaks Finnish fluently, I've videos of his lectures about Linux from the 90s at Helsinki University. Had I not known who he was, I would have not guessed he was of the Swedish-speaking minority (either that or I wasn't paying attention, I saw them ten years ago). You can find some videos on YouTube, no doubt.
Linus has excellent proficiency in Finnish; his intonation is distinctly that of a Swedish-speaking native but that is just a matter of style.
But then there are Finnish rock stars who lived a year in Stockholm and then pretended they've forgotten all about Finnish language. (Andy McCoy of Hanoi Rocks, I mean).
