MP5
Developed by Heckler & Koch in Germany, the MP5 is 9mm submachine gun. As you can see below, the MP5 in MW3 will look slightly different than the MP5 found in COD 4 and the MP5K found in MW2. This time around, the gun will be larger in length. The MP5 will be unlocked from the start in MW3.
UMP
The UMP will be returning in MW3. This SMG was also designed by Heckler & Koch. UMP stands for Universal Machine Pistol, or Universale Maschinenpistole. The UMP 45 first appeared in Call of Duty Modern Warfare 2. It was by far the most powerful weapon in the Submachine Gun Category. The UMP will be available from Level 1 in Modern Warfare 3.
PP90M1
The PP90M1 SMG is a new addition to the Call of Duty series. Developed in Russia, it is a helical variant of the AK74u. This weapon was designed by the KBP Instrument Design Bureau in the 1990s. In case you didn't know, a helical magazine extends the drum magazine design so that rounds follow a spiral path. This allow a large ammunition capacity in a small compact package. This SMG will be available from the beginning.
P90
The P90 (aka the FN P90) returns in Modern Warfare 3. This SMG featured in both COD 4 and MW2. Unlocked at Level 38, the P90 boasts a large magazine and a very high rate of fire. Although, it isn't as powerful as the MP5 or UMP. This weapon was designed and developed in Belgium.
PM-9
The Minebea PM-9 is a new addition to the COD series. Developed in Japan, this SMG is based on the mini UZI; although it looks and handles differently. This weapon is unlocked at Level 56.
MP7
The last SMG to be unlocked in MW3 is the MP7. This SMG is unlocked at Level 74. Like the MP5, this weapon was produced by Heckler & Koch in Germany. It is a direct rival to the P90. This submachine gun is used by the German Army and the Norwegian Defense forces.
M4A1
The M4A1 is unlocked from the start. It is a fully automatic Assault Rifle that is popular among special forces units. This weapon was also featured as an Assault Rifle in Modern Warfare 2.
M16A4
In MW3, the M16A4 will be available from the beginning. It will fire a 3-round burst, just like it did in MW2. This weapon is more effective at long-range combat.
SCAR-L
In the previous Modern Warfare game, we were introduced to the SCAR-H Assault Rifle. This time, in MW3, we will be getting a chance to use the SCAR-L. H stands for heavy, whereas L stands for Light.
CM901
The CM901 is unlocked from the beginning. Developed by Colt in the United States, this weapon is based on the M16 and the M4. In case you were wondering, CM stands for Colt Modular. 
Type 95
The Type 95 is a 3-burst Assault Rifle, just like M16A4. In MW3, you will be able to unlock the weapon at Level 32. This gun was developed in China.
G36c
The G36c was first featured in Call of Duty 4. It has since been confirmed that it will be returning in MW3. The gun can be unlocked at Level 42. This weapon was developed by Heckler & Koch in the early 1990s. The letter c stands for Compact and the weapon originates from Germany.
ACR 6.8
The ACR will be returning in MW3. Many Call of Duty fans will remember how accurate the ACR Assault Rifle was in MW2; as it had virtually zero recoil. This gun was designed by Magpul Industries in the United States. The ACR 6.8 can be unlocked at Level 50.
MK14
The MK14 Assault Rifle is semi-automatic. In MW3, it can be unlocked at Level 60. This is an enhanced Battle Rifle. Developed in the United States, it is currently used in Iraq and Afghanistan. Originally built to be used by the Navy Seals.
AK-47
The AK-47 is a fan-favorite that has been present in the last three Call of Duty games. In MW3, it can be unlocked at Level 68. The AK-47 was developed in the Soviet Union. This is one of the most-used Assault Rifles in the world.
FAD
The FAD is the last Assault Rifle to be unlocked in MW3. It can be unlocked at Level 78. This weapon was developed in Peru. It was designed by Salomón Braga Lozo from SIMA Electronica.
MW3 Mapas
Aqui está uma lista oficial dos mapas multiplayer encontrados em MW3.
Arkaden
Bakaara
ilícito
carbono
cúpula
crise
caído
capacete de segurança
intercâmbio
Lockdown
missão
posto avançado
resistência
Seatown
subterrâneo
aldeia
Libertação - Ver passeio através de Libertação mapa
Piazza - Ver-Walk através de mapa Piazza
Layouts de mapas de MW3
Underground?
Could this be a screenshot of the Underground map in MW3? It would make sense. Although this could be a single player mission or a spec op mission.
Carbon
Here is a screenshot of the Carbon map in MW3. Interesting to note that it is shown in both day and night. Could this mean that the day/night of the maps in MW3 will change according to the time of the player?
Here are another two screenshots of the Carbon map. One of the pictures looks like "map art".
This page will be modified as more information about the MW3 maps is released. Until now, we can only speculate on what the maps will look like.