tl;dr version: Jonathan Ross was asked to host the Hugos, the internet exploded over how he shouldn't, he almost immediately turned it down and the internet kind of kept on exploding.

On March 1, 2014, the World Science Fiction Convention (LonCon3) announced that Jonathan Ross, a longtime SF fan and tv presenter, would be presenting the Hugo Awards. Immediately, many people began posting their dismay that someone with a history of controversial behavior would get such a position, with the implication that he would make rude statements about women and minorities as the host. Farah Mendelsohn, a member of the LonCon committee, resigned in a now-deleted post which gave some the impression that Ross was mainly known for being offensive to generate publicity, similar to Howard Stern, which no doubt pressed many who were not familiar with Ross to protest the choice of an obviously unsuitable host. After about three hours (and an awkward insult to a fan who, Jonathan Ross announced that he was stepping down.

Here is a post that gives a descriptive timeline of events. A shorter timeline is given here.

At one point, Seanan McGuire commented “Wait. WAIT. They're letting JONATHAN ROSS present the Hugos? WHAT THE FUCKING FUCK” and “I’ve really enjoyed knowing that, were I to be nominated for a Hugo, the host wouldn’t see me and make fat jokes. Like, that thought has actually crossed my mind, when shopping for Hugo dresses, ‘The host won’t mock me’.” Despite not actually tweeting anything before Ross announced that he was stepping down, the similarity to other speculation about what Ross might do and McGuire's fame within fandom led to her comments being taken as at the forefront of the fans who called for him to step down, even in mainstream media publications. Ross's daughter tweeted at her to counter the accusation that Ross is an habitual fatshamer, and Jane Goldman (Ross's wife) angrily ticked her off for not responding to her daughter, and then deleted her account.

Links:

Guardian article on the matter, including Neil Gaiman's “disappointed” response to fandom's own response

Independent article, giving the text of Goldman's tweets

International Business Times article, with text of some tweets against Ross

New Statesman article, discusses the changing nature of SF/F fandom

Storms and How They Start, Gaiman's response. Gaiman sent the invitation to Ross in the first place, and he notes that the con should have all been in agreement before asking Ross to host and should have informed him and his family of the potential shitstorm in the first place.

Let He Who Is Without Sin, a rundown and response. Points out that people assumed the outrage was correct even when they had no idea who Ross was, and that Ross is a member of the SF/F community.

…Because this isn't how I want my community to be. The shift from “this person is doing something objectionable right now and we have to stop it,” to “this person said some objectionable things some years in the past and so he's not welcome among us,” is one that gives me great pause. You know who else has said some objectionable things in the past? Me. You know who else? You.

[…]

I'd especially not like to be in a community that says “You've screwed up before, so you're definitely gonna screw up again next time. Get lost, asshole.” Which looks to me like what ultimately happened in the Ross situation.

Seanan McGuire's Angry Mob, a post that generated some discussion on the meme. The consensus seems to be that it's good that he's pointing out that McGuire didn't start the fire, but that he's being extremely condescending in the name of feminism to women who don't like what she said.

Links to meme discussions:

Have we done Jonathan Ross/Hugo wank yet? (3/1/2014)

Hugo/Jonathan Ross wank - the sequel (3/3/2014)

Unpopular Opinions subthread (3/6/2014)

Rossgate continues, Gaiman shakes a finger at us all (3/7/2014)

rethinking an opinion - the Hugos (3/8/2014)