According to "Noandish":http://www.noandish.com/com.php?id=199 , Ali Khamanei, the Supreme Leader, has asked the Guardian Council to reassess the applications of the main reformist candidate, Mostafa Moin. However it's not confirmed yet.
Update: + ISNA has confirmed the report and has published "the letter":http://www.isna.ir/Main/NewsView.aspx?ID=News-531553 . It strikes me that Khamanie has lost his grip on some radical factions of conservatives and they've started to publically challenge him.
+ "Shahram Kholdi":http://secularcaniranik.blogs.com/scaniranic/2005/05/correspondence_.html has translated the letter, and has provided more detail about the whole story. Here is the translated version: bq. Your Excellency, Ayatollah Mr. Janati, upon greetings, salutations, and with the appreciation of your efforts in ascertaining the qualification of the candidates for the Ninth Presidential Elections. bq. Whereas, in due accordance with principles of the law, it is desirable that all the individuals in the country who enjoy various political views are given the opportunity to participate in the great test of the elections, hence, it appears that the qualification of Mr Dr. Mostafa Moin and Mr. Engineer Mehr-Alizadeh can be reviewed. bq. May Peace Be With You, bq. Sayyed Ali Khamenei bq. 23 May 2005