Rabbi Richman and Rabbi Winston discussed the 'inverted nuns' in this weeks Parasha.
There is a wikipage which discusses this...
http://en.wikipedia.org/wiki/Inverted_nunI normally don't use Wiki as a source for Jewish thought, but this page includes this description:
Rabbinic basisThe Talmud records that the markings surrounding Numbers 10:35–36 were thought to denote that this 85 letter text was not in its proper place. One opinion goes so far as to say that it would appear in another location which discusses the order of tribal column, with the position of the Ark already stated there.
The 85 letter text found between the nuns is also said to be denoted because it is the model for the least number of letters which constitute a 'text' which one would be required to save from fire due to its holiness.
The tractate Shabbat in the Talmud says regarding the inverted nuns:
It is taught in a baraita: "ויהי בנסוע הארון ויאמר משה" – The Holy One, blessed be He, placed signs above and below this portion, to say that this is not its place. Rabbi [Judah haNasi] said: It was not for this reason, but rather because it is an important book in and of itself.
—Shabbat 115b–116aSifrei explains these "signs":
It was marked with points above and below.
—Sifrei[9]
The Talmud continues, stating that as this section is a separate book, the portions of Numbers before and after it also count as books and thus the Torah contains seven books in total:[1][9]
For R. Shemuel bar Nahmani said in the name of R. Yohanan: “She hath hewn out her seven pillars” (Proverbs 9,1) – these are the seven books of the Pentateuch; according to whom? According to Rabbi [Judah Hanasi]
—Shabbat 115b–116aBar Kappara is known to have considered our Torah as composed of 7 volumes in the Gemara "The seven pillars with which Wisdom built her house (Prov. 9:1) are the seven Books of Moses". Genesis, Exodus and Leviticus and Deuteronomy as we know them but Numbers was really 3 separate volumes Num 1:1 to Num 10:35 followed by Number 10:35–36 and the third text from there to the end of Numbers.
It also suggests that the inverted nuns may suggest the Hebrew word ner, meaning 'a light'.[10]
Rabbi Shimon ben Gamliel states that in the future this section will be moved to "its [proper] place", and Rav Ashi explains (Shabbat 166a) that this is 'in the [chapter on the] banners', referring to Numbers 17:2:[1][11]
R. Shimon Ben Gamliel says: This section will be uprooted from its place and written in its rightful place in the future (but for now it is in its correct location). Why is it written here? So as to separate between first and second retribution [3]. Second retribution is "and the people grumbled". First retribution is "and they traveled from the mountain of G-d (i.e., they eagerly run away from G-d's presence)". Where is it its appropriate place? R. Ashi says: In the section on encampments
—Shabbos 115–116The Mishnah, in tractate Yadayim, states:[11]
A book that became erased and there remain in it 85 letters, like the section:and it was when the Ark was carried", renders hands impure
—Yadaim 3,5According to Midrash:[11]
These verses were incorporated in to the Torah from the prophecy of Eldad and Meidad. Their prophecy so remained and was explained by the Ezekiel: "So says the Lord, G-d. Are you the one of whom I have spoken in the days of yore through prophets of Israel. And some say that there was a hidden book (of prophecy).
—Midrash Chaseiros V'Yoseiros
The two nuns are similar to khaf and reish – to say that they are Ach and Rak (Only and however). Ach and Rak always exclude – to say that this is not the place of this section. Rebbi says because it is a book of its own.
—(Lekach Tov)Maharshal ruled that the Talmud only mandates the usual break for a parashah section, and Torah scrolls with extra letters are passul (unfit for ritual use).[7] Rabbi Yechezkel Landau, however, defends the custom, stating that punctuation such as inverted nuns don't count as extra letters and thus don't invalidate the scroll.[7]