While doing some reading last night, I came across a few canonical tidbits from James VanderKam's An Introduction to Early Judaism.
It is very likely that there was not a Bible in the second temple period - that is, an accepted, defined, and closed corpus of authoritative texts - but there is no doubt that there were some books widely held to contain divine teaching. [p. 213]
It is important to remember that the production of texts and the canonization of authoritative texts was a long and complex process. The text of the scriptures, therefore, did not fall out of the sky, as it would seem, but took a process of being embraced as authoritative first, then moved on to a more canonical status. What we need to realize is that there were many more texts that were seen as authoritative, to varying degrees, than were ultimately placed in the canon. I think we also need to agree with VanderKam in the fact that the canon was not even closed within the time of the second temple period.
VanderKam also highlights, very succinctly, the impact of the Dead Sea Scrolls on our understanding of texts and canon:
One of the great contributions made by the Dead Sea Scrolls to our knowledge about biblical books is that they have documented the existence of divergent Hebrew texts of certain scriptural works. That is, there was not a single Hebrew text of each of the Hebrew Bible/Old Testament; in some cases, such as the book of Jeremiah, there were Hebrew copies that diverged widely from each other. There was a shorter, probably more original version and one that was longer by about one-eighth and that had some material, such as the oracles of the nations, in a different place (in the shorter version they follow 25:19; in the longer one they are chaps. 46-51). This shorter version of Jeremiah had been known from the Greek translation of the book; now it can be seen that the Greek was not a free reworking of the one Hebrew original but was a faithful rendition of a Hebrew base text that diverged considerable from the one found in the traditional Hebrew Bible (called the Masoretic Text)...
We have no evidence that anyone was concerned that the different copies failed to agree word-for-word, although from some of the Qumran commentaries it is apparent that the expositors were aware of variant readings. Rather than bemoaning these, they at times exploited them in their explanations. [pp.215-6]
The fact of the matter is that texts, even the canonical texts, had variant readings in the Second Temple Period and this fact does not seem to be an issue for the faithful of the day. On the contrary, they not only embraced textual variants, they employed them in their interpretive venture. Imagine what kind of chaos that would create today, especially with our fascination with inerrancy and such.
There might come a day when we need to reconsider the versions of our canonical texts, in light of these textual finds. Perhaps it has already begun.