What are the connotations of the phrase "be'Etzem ha'Yom ha'Zeh"?
Ramban (on Pasuk 28): Literally it means 'on this very day', and it comes to teach us that, despite the intrinsic connection between the Yom-Tov and the Sefiras ha'Omer and the Minchah Chadashah mentioned earlier, the day itself is a Yom-Tov, irrespective of the Sefiras ha'Omer and the Korbanos. 1
Targum Yonasan: It is a hint that if we observe the above Mitzvos, we will merit to live and experience Shavu'os. 2
Oznayim la'Torah #1: It implies that one should be careful to celebrate Shavu'os on the correct date - on the fiftieth day of the Omer - since it does not fall on a specific date.
Why does the Pasuk insert the phrase "Chukas Olam be'Chol Moshvoseichem"?
Ramban and Seforno: Refer to 23:14:3:1*. 1
The Oznayim la'Torah explains that this is necessary, because we would otherwise have thought that, since Shavu'os falls fifty days after the bringing of the Omer, nowadays, when the Omer is not brought, Shavu'os does not apply.
