Pop quiz: Which of these logos belongs to Sony Ericsson and which belongs to Clearwire? If you don't know the answer, then you've justified the federal trademark lawsuit Sony Ericsson just filed.
Apparently Sony Ericsson is concerned that Clearwire might confuse folks by using a logo consisting of a "sphere with swirl marks" in the mobile market, so it's asking a court to prevent the company from continuing to use the logo in any way—and to grant some monetary damages.
Whether Clearwire's logos wind up being deemed as an infringement on Sony Ericsson's trademarks or not, my heart goes out for the company as I sincerely doubt it's in the best state to deal with the cost of a legal battle right now. [Sony Ericsson Complaint (Warning: PDF) via Northwest Innovation via Engadget]