It looks like it's going to be an intriguing weekend at the box office. 

After a mammoth opening on Wednesday, "Harry Potter and the Half-Blood Prince" is settling into a strong first week run.  According to Box Office Mojo, the critically acclaimed sixth installment in the franchise grossed an impressive $26.8 million on Friday to reach $107 million in only three days.  The fantasy flick could finish with a five-day total of $160-170 by the end of the weekend.  Impressive, but nowhere near the $200 million "Transformers: Revenge of the Fallen" grossed in the same time period a few weeks ago.  Still, "Half-Blood Prince" is a massive hit worldwide and with the cash cow "The Hangover" well on its way to $250 million domestically, its all smiles over on the Warner Bros. lot.

Far behind in the second slot was "Ice Age: Dawn of the Dinosaurs" with $5.4 million.  The Fox family flick is slowing down with $139.7 million total, but should finish somewhere inbetween the original's "$175 million and "Ice Age: The Meltdown's" $195 million.

Proving robot love won't die, "Revenge of the Fallen" was in third with another $4.1 million to add to it's $354 million domestic gross.  $400 million is not out of the question, but Paramount Pictures is probably just as happy the Michael Bay actioner is looking at an eventual global cume past $800 million. 

With a reportedly massive 81% drop in fourth place is the controversial Sacha Baron Cohen comedy "Bruno" with only $2.8 million.  After a strong $30 million opening last week, the mockumentary is fading fast and could end up only between $60-70 million domestic.

Knocking on the door of the top ten in only 27 theaters is Fox Searchlight's "500 Days of Summer."  The unconventional romantic comedy found $265,000 and a stellar $9,815 average on it's opening day.  The Sundance Film Festival favorite looks like it's going to live up to its billing as the sleeper hit of the summer.

Look for final weekend estimates tomorrow on HitFix.