If you're referring to the Vanguard Cash Deposit program, yes, I have received emails about it. Offering 3.7% APY and FDIC protection.
Not interested, personally, since I'd rather keep my cash in VFMXX at 5.29%. I have no need for check-writing or FDIC protection for the funds I keep there.
EDIT: I see now that the Cash Plus program is distinct and different from the Cash DEPOSIT program. I don't see myself being too interested in either one at this point.