Source: News.com _________ Facebook, which says it's making a big announcement this week, is trying to keep details under wraps. But that hasn't stopped the Internet's rabid gossip mill. Last month, word began to circulate that Facebook was working on a deal to introduce third-party widgets (embeddable code containing external content like music or video) into its member profiles. And early in May, several blogs reported that Facebook was rumored to be launching a music service on Monday--a bit of speculation that does not appear to have been true. But one thing that is confirmed is that Facebook will hold an event in San Francisco on Thursday that the company touts as "the unveiling of the next evolution of Facebook."