I had an epiphany recently, related to the fiction in our slush pile...
As you probably know, the Electric Spec editors are also authors. This week I've been working on a story for a contest. In the contest rules, the editors give examples of the types of dramatic first lines they desired. I gradually realized they were all 'telling.' The editors didn't use the word 'telling' but that's what they were.
Something about this seemed familiar...
Sure enough, in 2006, I wrote a blog entry Short Story First Lines with a bunch of first lines from award-winning short stories. (Not all the links therein still work. Try American Book Review's Best Novel First Lines, for example, instead.)
A lot of these first lines are 'telling,' as well. Eureka!
Therefore, I can say with confidence: consider telling in your first line!
Of course, here at Electric Spec, we think you should have some showing in your story, as well--but that's another blog post.
Good luck with your submissions!