Dedexer got competition! Not one but immediately two - smali and baksmali is a DEX assembler/disassembler pair. The programs are brand new and - like Dedexer - they are also based on a Jasmin-like format. I tried them very shortly, the disassembler - baksmali - worked correctly and indeed produced an output similar to dedexer but I could not compile the output of baksmali back to DEX format with the assembler - smali. The disassembler does not handle ODEX files either.
The initiative is indeed valuable, however, and I encourage every reverse engineer out there give the new tools a try.