For some reason I can't make the video of the rappers from Nahr el-Bared to post here, so I'll just link to the post from Decentering Damascus. It's filmed at an event at Badawi refugee camp (Tripoli, Lebanon) organized by displaced Palestinian youth from Nahr el-Bared refugee camp. I'll try to get some help in translating the lyrics. Meanwhile, check it out. The offspring of Palestinians displaced by the creation of Israel in 1948, themselves displaced again by the fighting between the Lebanese Army and Fateh al-Islami.
Meanwhile, check out this flyer for the "Anti-Crise" festival, to be held at Sanayeh Garden in Beirut on September 8, and at the port of Tyre on September 9, which features among other artists two Palestinian rappers from Lebanon, RAy (of I-voice--check out I-voice's free downloads at their myspace page) and H2z (you can listen to his raps here).
Finally, visit Ramallah Underground for more Palestinian rap. I've not visited this site for awhile and they've got some great new stuff.