According to TheReligionofPeace.com:

The Quran also gives devout Muslim men license to capture women and use them as sex slaves, lest four wives prove insufficient.

The same site also makes the following claim:

The Qur'an actually devotes more verses to making sure that Muslim men know they can keep women as sex slaves than it does to telling them to pray five times a day.

As evidence, it provides the following verses (among others):

Qur'an (33:50) - "O Prophet! We have made lawful to thee thy wives to whom thou hast paid their dowers; and those (slaves) whom thy right hand possesses out of the prisoners of war whom Allah has assigned to thee" This is one of several personal-sounding verses "from Allah" narrated by Muhammad - in this case allowing himself a virtually unlimited supply of sex partners. Others are restrained to four wives, but may also have sex with any number of slaves, as the following verse make clear:

Qur'an (23:5-6) - "..who abstain from sex, except with those joined to them in the marriage bond, or (the captives) whom their right hands possess..." This verse permits the slave-owner to have sex with his slaves. See also Qur'an (70:29-30).

Qur'an (4:24) - "And all married women (are forbidden unto you) save those (captives) whom your right hands possess." Even sex with married slaves is permissible.

Bukhari (62:137) - An account of women taken as slaves in battle by Muhammad's men after their husbands and fathers were killed. The woman were raped with Muhammad's approval.

(Many other verses referenced at the links above).

Is this an accurate understanding of these verses? If so, is this behavior still practiced and/or permitted? And if not, why the change?