Does anyone actually publish "structured proofs"?
While most people use more traditional proof styles, the more exhaustive structured proof style that Lamport proposes seems to be adopted, at least in spirit, by machine-assisted proving systems like Coq and Lamport's own TLA+.  By bringing a very non-intuitive player into the loop (the machine), these systems force the mathematician to be much more explicit about every step and assumption, and encourage hierarchical structure by their use of programming-language style syntax.  

These proving systems are typically quite expensive to use, and you generally wouldn't want to put their lengthy proofs into the middle of a paper---attaching as supplementary information is more the way to go.  They are, however, proving to be quite valuable in critical applications where dealing with every possible edge case is important, such as in the design of microprocessors or cryptographic protocols.