This far only Nokia provides Smart Messaging support. Some manufacturers provides support for EMS, but mostly different kind of EMS-formats. Sagem has own format for example for ringtones, as well as Motorola has before EMS-support. Some of the phones support also SMAF, so the field is very fragmented.
Good document for you might be "Nokia Phone Messaging Characteristics v1.2" at http://www.forum.nokia.com/main/1,35452,1_2_5_3,00.html