There's been an active thread for the past few weeks called "Stealth Nerf to Elemental," wherein Elemental shamans voice concerns that their DPS fell in patch 3.1. Blizzard assures us that there was no intention to nerf Elemental DPS in the patch, and that they couldn't find any bugs.
However, they must have come to the conclusion that Elemental was a bit low, because they're hotfixing in a buff to Lightning Overload. Currently, it has a 7/13/20% chance to proc; when the hotfix goes in ("sometime over the next couple of days"), it will be raised to an 11/22/33% chance, although the tooltip will not change (this will be fixed in a patch).
Ghostcrawler's estimate is that this will be about a 5% to a raid-buffed shaman, but they'll keep an eye on it, and further buffs will ensue if necessary.