My thoughts exactly. The 17MM was a 'cheap' way to save face for big-name investors and "celebrities" who'd been duped. Circle-jerk money.
"Angel Investors and Advisors include; Ashton Kutcher, Betaworks, Brian Chesky, Hosain Rahman, Jessica Powell, Joanna Shields, Josh Kushner, Mark Pincus, Matt Mullenweg, Seb Bishop, Shakil Khan, Spencer Hyman, Stephen Fry, Troy Carter, Vivi Nevo, Yoko Ono and many more. We are also working closely with News Corporation on the summarization of their content."
Edit: actually, reading all of the comments on this page, I think my explanation is less likely than the "summly may have had a special license, and SRI couldn't be sold unless summly was acquired as well" (without resulting in lawsuits or sub-licensing deals) and/or "a nice way to pay more for SRI via the backdoor" (artificially increasing the value of the summly stock they held -> more $$ for SRI).
Do we know how much stock SRI owned of the company? Perhaps they provided services in exchange for summly shares? Wouldn't be the first time.
Their will be follow ups and some of them might lean towards Yahoo on the next acquisition.