There will not be a season 3, I can assure you all of that. (sides manga's 1000X better anywho)
Also Rosario+Vampire Season 2 Volume 8 comes out stateside in April, be sure to snatch yours up when it comes out.
*Looks at abouve posts* hmm guess these youngins need some clarifcatifiyn (hmm I just made up a new word. )
The Rosario+Vampire Manga is still ongoing in Japan, dunno what you mean by Volume 11? the 1st series/season only has 10 volumes, the series is currently on its second series/season (yes mangas can have seasons too) and 7 volumes of season II are available in the U.S. and as stated earlier Volume 8 comes out in April. So in total as of April 18 volumes of the manga will be available in the states.