That was an interesting read and it bring up a good point, where the does the dianoga come and go from without getting crushed by the trash compactor? The 2 articles linked do add interesting insight to that question, esp. the one from McSweeney's which goes into the design and necessity of the trash compactor itself.
For some reason, maybe it came from the EU, I got the impression that the dianoga was highly compressible, like a squid or octopus. It does seem to go away right before the walls start closing in so that explanation makes sense too. I originally had idea that the Force had something to do with it letting Luke go.