As Wikipedia notes, 
"[[http://en.wikipedia.org/wiki/SOAP|... SOAP ... is a protocol for exchanging XML-based messages ...]]"
It's nominally language-independent (and platform-independent,
encoding-aware, transport-neutral, ...).

Many Pythoneers are ... reserved about the complexities of and incoherent design of SOAP; Rob Riggs
rants for many when he writes
"[[http://lists.community.tummy.com/pipermail/frpythoneers/2007-April/001352.html|... they invented SOAP for brainwashing software architects.]]" 

The page on [[WebServices]] says more.