1) Seeing something powerful in contextual data surrounding phones and mail (perhaps the two most basic forms of communication ever). 2) Both are part of the Microsoft Accelerator Program- The two of them also use Microsoft technology- .NET and Outlook (C#, I think). For some this may go against them. 3) Both have founders that are very nice guys (but you definitely wouldn't want to compete against them). 4) Both are VC-backed and they never sold out earlier like other YC companies, which just shows their relative tolerance of risk.