An interesting addendum to the story of Lo B'Shamyim Hi, It is not in
heaven, or the oven of Achanai is the symbolism inherent in the story.
Snakes
Firstly, the baker, Achanai enquires as to whether his oven is Kosher or not. Achanai comes from the same Hebrew root as the word Nachash, which means snake; in fact many translations of the Talmud do away with the name Achanai and refer to this story as the oven of the coiled snake. Instantly we know that there will be divisions between man and man (from the story of Moses and the servants of Pharaoh and the rods which turned into snakes), and we know that there will be divisions between man and G-d (from the story of the snake and the apple in the Garden of Eden).
Trees
The image of the tree being ripped out of the ground in agreement with Rav Eliezer backs this up, as trees being ripped out of the ground are also bad images. For example, the Bar Kochba revolt is not often looked at as a generally good thing for Judaism, and at one point, the entry requirement for Bar Kochba's army was the ability to rip a Cedar of Lebanon tree from the ground whilst on horseback. In addition to this, this also conjures up images of the Tree of Life/Knowledge and the snake, as previously mentioned.
Eliezer
Throughout the Talmud, there is one thing common about many of the stories that feature Rav Eliezer: He is almost always wrong! In fact, he was eventually excommunicated. If you know what you are reading, you know what the outcome will be right at the start of the debate. The question is, why will Eliezer be wrong?
The walls
Is the passage about the walls half collapsing but still standing alluding to the destruction of the Temple, given that the southern wall and part of the western wall still stand? Could it be saying that an argument of such magnitude could be catastrophic for Judaism?
The ending
It is worth noting (and, dare I say it, nodeing) that Natan and Elijah came several hundred years after this discussion. So why was this bit tacked onto the end? Try rereading the story without the verse about 'My children have defeated me'. We are presented with Rav Yehoshua basically shouting at G-d at the end, and there being no conclusion as to who is right and who is wrong. With this piece, not only do we find that Yehoshua is not a bad guy, and is working within G-d's framework, but we also get the answer to who really was right on this.
The message
This story is usually interpreted to mean that Halacha can be changed, but only by a majority of the Rabbanim of the Sanhedrin. Having said that, the Talmud was written after the Sanhedrin had disbanded, so why was it even included?
The Story : My thoughts
I think this story was included because it can be studied over and over again, and everyone can get something out of it, from novices to experienced learners. I don't think there is really any Halacha attached to it, it is really an exercise in learning Talmud, all the key elements are there, Eliezer, G-d, a really meaty debate and a clear answer.
Maybe that answers the final question about the story, why have I learned it at least 15 times in the last year?!?!?!?!