It was made official today, and announced on the Finnish elite league team's Twitter account just minutes ago: Erik Karlsson has signed with Jokerit of SM-liiga. The team has also issued a press release on their website (Google translation available here).
It was widely thought that Karlsson would sign with his former SEL team Frölunda, and the two sides were reportedly in negotiations recently, but the reigning Norris Trophy winner opted instead to head to Finland. Jokerit is managed by former Ottawa Senators player, scout, and Director of Player Personnel Jarmo Kekalainen, and former Senator Jarkko Ruutu is also on the team. The contract is a month-to-month deal, apparently; it's not clear what that would mean if the lockout ends mid-month, nor is it clear what Karlsson will be paid for the duration of his time with Jokerit.
Aside from Karlsson and Ruutu, Jokerit players with NHL experience include Valtteri Fillpula, Ossi Vaananen, Riku Hahl, and Antti-Jussi Niemi. Chicago Blackhawks prospect Teuvo Teravainen (drafted 18 overall in 2012) is also on the squad.
Karlsson's the fourth Senators player to sign overseas for the lockout, following Sergei Gonchar and Kaspars Daugavins, who both signed on to KHL squads, and Jason Spezza, who's playing in Switzerland.