On the day of the first fruits, your Feast of Weeks, when you bring an offering of new grain to the Lord, you shall observe a sacred occasion; you shall not work at your occupations. -Numbers 28:26
Of the three pilgrimage festivals, Shavuot seems to have been the most difficult to translate into a meaningful holiday for Diaspora Jews. Pesach, with the seder, with its symbolic foods and powerful story; Sukkot, with its colorful symbols and observance - and both of these also have strong seasonal resonances of spring and fall (at least in the Northern Hemisphere) - while they may not be as central in Jewish consciousness as the High Holy Days, are nevertheless easy to relate to and remember. Poor Shavuot has been a harder sell. It doesn't have a clearly defined date in the Torah; it is only one day; it was, according to the Torah, completely tied to agriculture and to the Temple cult; thus, once the Temple was destroyed and our lives were not directly linked to the agriculture of Israel, Shavuot was orphaned. Fortunately, the rabbis figured out that the timing of the day fit with the timing of the revelation at Sinai, and, post-biblically, Shavuot took on the additional meaning of the Festival of the Giving of the Torah. This in turn led to the development, in the middle ages, of the "tikkun layl Shavuot," the custom of staying up into the night to engage in intensive study of Torah, as a kind of reliving of the revelation. And, since the prescribed texts for study in the tikkun represented the whole historical spectrum of traditional text, the tikkun was also a reaffirmation that all Torah learning, in all generations, originated at Sinai.
Growing up in a Reform congregation, Shavuot was not exactly a major event; indeed, if not for confirmation, I doubt that most of us would have known it existed (and even then, it was generally observed on the nearest weekend, not on the holiday itself). Confirmation was a brilliant move - it made Shavuot, whose timing was opportune, into graduation. Without this content, the day would surely have just gotten lost in the commotion of the end of the school year.
For the Zionists who rebelled against Jewish religion, the obvious direction for Shavuot was the restoration of the biblical format, and for years, the First Fruits Festivals on kibbutzim, with elaborate pageants and parades displaying fruit and tractors and babies, and joyous singing and dancing, were a tourist attraction for urban Israelis and a symbol of what the return meant. For urban school children there were also first-fruit pageants and celebrations of the second-graders receiving their first Bible text. The tikkun was the preserve of the Orthodox for the most part - and of course, for everyone there was the [still essentially unexplained] custom of eating dairy foods, especially blintzes and cheesecake.
Over time, the divide has blurred, and in recent years, tikkunim are all the rage. I could have gone to at least one every night for the entire week before Shavuot in our area, not to mention the options all over the landscape on Shavuot eve itself. In Jerusalem, one can spend the whole night wandering from tikkun to tikkun, in homes, synagogues, community centers, educational institutions, of every religious and ideological flavor. Most of these gatherings use the name, but ignore the traditional format. They are simply evenings of study for the sake of study (and fellowship), and themes and topics are endless. The night before Shavuot eve our local recreation center put on an evening where the more spiritual topics tended to Zen and Yoga (raising the question - are Zen, and Yoga, in Hebrew at a tikkun, Torah?).
And of course regarding capitalism and Torah, the dairy industry spends months in preparation, and for the week before Shavuot there are long lines at the cheese counters, and free dairy cookbooks at all the supermarkets, and special deals on new flavored cream cheeses (e.g. this year, roasted eggplant cream cheese).
So how did we get from "I am the Lord your God" to roasted eggplant cream cheese? Isn't that what a Jewish state is all about?