I mostly found it, unsurprisingly, on the BBC. The summary of the judgement is worth reading, and I suppose my legally minded readership wouldn't mind going deeper into the whole judgement, which is accessible from that page. I didn't, as it's 70 pages long, although no doubt written in better prose than The Da Vinci Code.
A few further points, if I might:
* Baigent and Leigh were not suing Dan Brown. They were suing his (and their) publisher, Random House.
* Their claim was not "Dan Brown stole stuff we made up in The Holy Blood and the Holy Grail" although it's fun to pretend that they're backtracking on their claim to have written nonfiction. Their claim was that Brown had appropriated the central theme and structure of HBHG for his novel -- much as if, say, someone had taken the structure of Doris Kearns Goodwin's new book about Lincoln's Cabinet and fictionalized it into a gripping novel. Under British law, at least, your effort in producing a work, fiction or nonfiction, is protected by copyright -- if The Da Vinci Code had actually begun with the Rennes-le-Chateau documents and finished triumphantly with the claim that Pierre Plantard was the Merovingian heir to Jesus' bloodline, Baigent and Leigh might have had a case. However, it mentions neither of those fairly key elements -- of Baigent and Leigh's list of 15 "key elements" making up their post hoc theme and structure, nine don't appear in the novel at all, including the nature of the Grail as bloodline. Baigent was forced on the stand to admit that he essentially didn't actually know what his own book said, and that his court filing was a tissue of lies and exaggerations. The book Brown actually ripped off much of the structure from, The Templar Revelation by Picknett and Prince, wasn't mentioned AFAIK.
* The copying and rearranging that Brown did do, and admitted to on the stand, wasn't part of the filing. In other "Dan Brown Is A Hack" news, he pointed out in a filing that all his books have the identical thriller structure, and further admitted to not knowing anything about his source material, including the sources, as it was passed to him in great undigested chunks by his research assistant and wife, Blythe Brown.
* Who did not take the stand, so the Browns' ludicrous claim to have not even read HBHG while plotting the novel went unchallenged. (In all fairness, HBHG doesn't appear in the bibliography of his original outline, and as an old-school bibliography padder from way back, the most likely explanation for its absence is that Brown didn't actually have a copy to hand then.) Though the judge drew the natural inference, as do I.
* Henry Lincoln, the co-author of HBHG, didn't take part in the suit "for reasons of ill-health." Or perhaps because he's on record as thinking Baigent and Leigh are delusional and wants no part of their foolishness. Either way, he's saved himself a chunk of money -- Baigent and Leigh have to pay not only all of their costs, but 85% of Random House's.
* Even if Baigent and Leigh had won, it wouldn't mean that you couldn't legally write bad thrillers about made-up facts. It would, quite possibly, have exerted a "chilling effect" on what publishers are willing to let you try. I imagine that publishers are already quite chary of letting you refer to the theology of Scientology in a novel, for instance, although I urge Dan Brown to add Thetans to his next opus. Such chilling effects do not necessarily depend on the remotest legal concerns, as Salman Rushdie will no doubt be happy to explain. But absent fanatical murderers, chilling effects are fairly fluky things.
* For example, although James Herbert was found (in a 1979 lawsuit) to have lifted great chunks of Trevor Ravenscroft's Spear of Destiny for his novel The Spear, it doesn't seem to have bothered Random House that Dan Brown jams wads of slightly-rearranged prose from HBHG and other sources down the throats of his various tedious characters. (See major_clanger's informative post on the Herbert case for some delightfully old-school British judging.)
* But, as someone who does his own fair share of ripping off delusional people, I'm pleased at the verdict in general. Although in the Guardian Nick Cohen aptly quotes Henry Kissinger on the Iran-Iraq War: "It's a shame that someone has to win."