There are about a dozen threads here now stating that Rooftop Rumble has been removed. It hasn't. It has simply temporarily disappeared from the pause menu mission list. Once you accept this job from Martin (or accept someone else's invitation to join the mission) and successfully complete it, it will once again be in your pause menu mission list.
UPDATE: The same is true of all the other missions that people are now claiming have disappeared, too. Just accept the missing mission from the relevant NPC or accept another player's invitation to that mission and once you've successfully completed that mission it will be back on your mission list.
UPDATE 2: Here's the same information, just released by Rockstar.
[Updated 3/26/14] Rooftop Rumble missing in GTA OnlineRockstar GamesToday at 12:00Question: I checked through my bookmarked missions in GTA Online, and Rooftop Rumble is not in the list. What happened to this mission?Answer: We are currently working on fixing an issue with Rooftop Rumble, and expect it to be available again within the next week. Apologies for any inconvenience.If you would like to receive an automatic email whenever there are updates to this page, please log into the Support Site and click Subscribe at the top of this page.Update 3/26/14:Rooftop Rumble is now available to play again in GTA Online. The mission may not be available from your pause menu. If that is the case, please follow these steps:1) Join GTA Online2) Call Martin and request a job.3) If you do not get Rooftop Rumble, try joining a Quick Mission from the pause menu.4) Repeat steps 2 and 3 until you enter a Rooftop Rumble lobby.5) Complete and pass Rooftop Rumble6) Return to Free RoamAt this point, Rooftop Rumble will be available to play from the pause menu as often as you'd like. The payout and RP for this job have not been adjusted.