They had a disagreement about the use of a condom, but it took several days before they reported it as rape to the police.

Here is an article about it: http://timesofindia.indiatimes.com/world/us/Sex-accusers-boasted-about-their-conquest-of-WikiLeaks-founder-Julian-Assange/articleshow/7068149.cms

"And an obscure Swedish law was invoked. It is sometimes called the "surprise sex" law. In essence, it holds that if a woman withdraws her consent at any point during intercourse, and the man continues, it becomes rape. This transition from consensual to non-consensual sex is what Assange is accused of. All this will have to be proved in the court — a Swedish one."

I might have read that the women have now changed their minds about pursuing this, but I could be wrong.

yes, the 2 women involved were persuaded by swedish authorities to divulge any 'dissatisfaction'; with their encounters with assange, which the swedish state then used without the consent of the women (ironic, huh?) to construe as rape. The women themselves are not pushing the charges. More granular detail in all the comments on the twitter feed in this posts link