Florean Fortescue’s ice cream might seem old-hat compared to Ben & Jerry’s latest lactic stylings. But, for thousands of aspiring wizards, its appearance in Harvard Square tonight will be—well, a novel experience.

Fortescue’s desserts have heretofore appeared only in Diagon Alley, a London locale that offers more enticing—if fictional—retail alternatives to the Square’s pedestrian Gap and CVS. It will finally be conjured into real-world cones, though, thanks to Toscanini’s (where else?)—part of a Square-wide effort to help bring Hogwarts to Harvard.

Square venues normally closed to weekend revelry are coming alive to celebrate the 12:01 a.m., Saturday, release of “Harry Potter and the Half-Blood Prince,” the sixth installation in the seven-year chronicle of Harry Potter’s career at Hogwarts School of Witchcraft and Wizardry.

Even Harvard’s Muggle halls of power have relented, allowing rising high-school juniors in the Secondary School Program to wander outside the Yard’s gates past their usual 12:30 a.m. curfew—but only if they return with book in hand.

At the Harvard Book Store, which has pre-sold about 400 copies, four propitious patrons—“one lucky student from each Hogwarts House”—will receive “Golden Snitches” redeemable for audio recordings of the penultimate Potter tome. The snitch, per Potter lore, is a small ball used in the sport called quidditch.

At Curious George Goes to WordsWorth, employees will serve up—for no extra charge—frothy butterbeer (presumably of a nonalcoholic, Hogsmeade vintage).

And at the Charles Hotel, guests who purchased the “Harry Potter package” (for a mere $299 per night) have the privilege of fishing their room keys out of an authentic Sorting Hat.

At 8 p.m., they are invited to join an estimated throng of 1,000 in the Charles Hotel courtyard, when the hotel teams up with the Harvard Coop to show the film version of “Harry Potter and the Prisoner of Azkaban,” the third title in the series that is, by now, old news to Dumbledore diehards.

Jennifer Z. Gong ’07 is one of those Hogwarts habitués. “Right now I’m sewing my robes for the party,” Gong said in an interview on Wednesday.

Her garment is standard Diagon Alley fare, worn by students of all four Houses. But Gong says she has recently been “leaning toward Ravenclaw”—that academic workhorse of Professor Filius Flitwick—although the slimy greens of her Muggle House, Leverett, have more in common with Slytherin.

While the Harvard Book Store plans to sell the 672-page hardcover for $23.96 and Curious George’s for $22.50, the Coop, which is backed by Barnes and Noble, will offer it for $17.99.

Gong and her friends will celebrate the release tonight at the Harvard Book Store, where Gong ordered a copy four months ago. She says she chose the store because it was “out of the way and less crowded” than many of its Square competitors.

Much of the Class of 2008 was only 12 when J.K. Rowling’s first novel, “Harry Potter and the Sorcerer’s Stone,” was published in the U.S., the beginning of a seven-book sensation that has made Rowling richer than the Queen of England and turned thousands of readers, like Gong, into Potter fanatics.

Some got on the Hogwarts Express train later, hooked by the series’ Hollywood incarnations.

“One night I just said, I wonder what the Harry Potter books are like, because I’ve seen the movies, and I felt underwhelmed by them,” said John S. Denton ’06, who became interested in the series about six months after the 2003 release of the fifth title, “Harry Potter and the Order of the Phoenix.”

Denton read the first four volumes as illegally-downloaded e-books, but bought the fifth and ordered the sixth on Amazon.com in January.

After midnight tonight, Gong faces a solid weekend of non-stop reading and preparing lists of cross-references with the earlier volumes. She hopes to begin the reading marathon on her walk back home from the Harvard Book Store. (She plans to carry a flashlight.)

Denton, however, has no time for herbology or occlumency this weekend.

“If I wasn’t taking [the Summer School’s] organic chemistry class, I would. Again, there’s that conflict between reality and fantasy,” Denton said.

—Staff writer Brendan R. Linn can be reached at blinn@fas.harvard.edu.