MTOM/XOP implementations/prototypes and use cases?

hi,

are there available any (open source?) implementations/prototypes  that 
validate proposed spec practicality (casual googling did not find any)?

isnt it important to follow IETF model for more than one proof of 
concept implementation or is it too early at this stage?

what is the current timeline for XOP/MTOM?

did anybody try to set some use case and test interoperability?

it seems that since conception of initial idea the description becomes 
more and more formal/complex/harder to read (like dependency on XML 
Query model which depends on PSVI from XML Schemas ...).

thanks,

alek