It is believed by some Muslims that suicide killers will receive sexual rewards in heaven. Other Muslims disagree with them and say it is a sin to commit suicide and therefore they'll not enter paradise according to this Hadith (Prophet's sayings) :

Bukhari Volume 2, Book 23, Number 445

Narrated Jundab the Prophet said, “A man was inflicted with wounds and he committed suicide, and so Allah said: My slave has caused death on himself hurriedly, so I forbid Paradise for him.”

But some Muslim apologists say that while suicide is forbidden in Islam, martyrdom for an Islamic cause is praised and welcomed according to the Quran: (3:169)

“Do not consider those killed [while engaging] in God’s cause dead. Rather, they live with their Lord, who sustains them!”

So, those who have died while blowing up innocent women and children are considered martyrs or suicide killers? I believe a peace-loving Muslim will call these people murderers whereas other Muslims will call them "martyrs". 

Anyway, where does this teaching that suicide killers will receive 72 virgins in Paradise come from? It is derived (loosely) from the following Hadith:

Sunan al-Tirmidhi Hadith 2562
"It was mentioned by Daraj Ibn Abi Hatim, that Abu al-Haytham 'Adullah Ibn Wahb narrated from Abu Sa'id al-Khudhri, who heard Muhammad saying, 'The smallest reward for the people of Heaven is an abode where there are eighty thousand servants and seventy-two houri, over which stands a dome decorated with pearls, aquamarine and ruby, as wide as the distance from al-Jabiyyah to San'a."

 Watch the interviews of these failed suicide bombers: