Just found this out, and it has been confirmed by executive producer Amy Berg: E! Online is reporting that Syfy has given Eureka one additional episode with which to wrap of the series.
Previously, when the tentative 6 episode 6th season was abruptly dropped, it was thought that there was no way to properly conclude the series – the 5th season finale is about to go in front of the cameras and there would be little time to completely rework the script and alter the production schedule, and we’d end up with just an incomplete show.
But now Syfy and the producers have reached an agreement for one additional episode, which will give them time to wrap up the series. They are working on the script now, and as Berg said on Twitter, “we’re ALL writing it”.