better late than never...
> Are the SFP socket MultiSource Agreement (MSA) compliant?
Yes, Me-3400 is MSA compliant (the SFPs are compliant to industry-standard SFF-8472 Multi Source Agreement (MSA) rather than the sockets). They do offer Digital optical monitoring (DOM) for some SFPs.
see:
http://www.cisco.com/en/US/prod/collateral/switches/ps6568/ps6580/product_data_sheet0900aecd8034fef3.html
> Can we use SFP transceivers made by other vendors in ME-3400 switch?
Official answer is NO. Whether they work or not is another story though.
Riccardo