After only eight episodes, Mahou Shoujo Madoka Magica has passed the original series of Suzumiya Haruhi no Yuuutsu as the most popular current anime ever on the Japanese discussion board 2channel.
The ranking is based on number of posts during an anime's initial run and up to three months after it. Here is the full top ten list (source):
#1 -- Mahou Shoujo Madoka Magica (465,000 posts)
#2 -- Suzumiya Haruhi no Yuuutsu 1 (464,000)
#3 -- K-On!! (359,000)
#4 -- K-On! (354,000)
#5 -- Angel Beats (342,000)
#6 -- Suzumiya Haruhi no Yuutsu 2 (283,000)
#7 -- Code Geass R2 (277,000)
#8 -- Minami-ke Okawari (254,000)
#9 -- Strike Witches (253,000)
#10 -- Strike Witches 2 (233,000)
Since the time the list was prepared, less than 24 hours ago, about ten thousand posts have been added to MadoMagi's total. The person who compiled the list did not count the six threads (6000 posts) that had been filled before the show began airing. The full total number of posts as of this moment is approaching 481,000.
It remains to be seen if this show can maintain the strength that Haruhi has. Posts about the two Haruhi series have just kept coming since they were broadcast in 2006 and 2009, and the total for both shows is now over 1,700,000 posts.
In any case, the show's high quality and the way it subverts the magical girl genre have obviously struck a chord with Japanese otaku.