TMZ reports that "Lennon Murphy, a singer-songwriter whose band is called Lennon, has been sued by Yoko for 'tarnishment' of her widow's name [sic] and for 'fraudulently' registering the name as a trademark." However, it rather appears that Yoko Ono (as she herself clarified) filed a petition for cancellation with the Trademark Trial and Appeal Board seeking to cancel Trademark Registration No. 2676604, based on Registration numbers 1769796 and 1488395 for the marks JOHN LENNON.
Petitioner claimed Murphy obtained her registration fraudulently, and that Murphy's mark dilutes and/or tarnishes her late husband's surname. Petitioner did not, however, make a section 2(d) likelihood of confusion claim in her petition (15 U.S.C. 1052). USPTO TTAB Cancellation number 92048785; filed 1/18/08.
The petition is unusual in certain respects. Whether the petitioner intended to bring a likelihood of confusion claim is unclear. When filing the petition to cancel electronically, petitioner did identify Section 2(d) as a cause, however the petition has no pleadings referring to likelihood of confusion.
Additionally, it is interesting that the substance of the fraud allegation is that applicant did not identify that her first name was Lennon. However that fact was disclosed in that she filed the application as an individual, in her own name, Lennon Murphy.
Lastly, according to TMZ, Murphy asserts that the band has a co-existence agreement to use the LENNON mark (Yoko gave her "blessing"), raising a possible acquiesence argument.
[Documents can be accessed via the USPTO Trademark website, by searching TESS for the above registration numbers and then clicking the TTAB tab.]