MMS is a non-proprietary, industry standard phrase and not limited to, or described by RIM

see phonescoop or see below

MMS

MMS (Multimedia Messaging Service) is a descendant of SMS (Short Messaging Service). MMS extends text messaging to include longer text, graphics, photos, audio clips, video clips, or any combination of the above, within certain size limits.

MMS is frequently used to send photos and videos from camera phones to other MMS phones or email accounts. Most camera phones have MMS, but many non-camera phones have it as well.

Many newer MMS phones also support SMIL, which allows various parts of an MMS message to be arranged into a small multimedia "slideshow" to be viewed on another SMIL-capable MMS phone.