Olson v. Halvorsen, (Del. Ch., Oct. 22, 2008), read opinion here. The Chancery Court decided an issue of first impression in the context of cross motions for summary judgment in this case: Does the statute of frauds apply to an LLC Agreement. The answer is yes.
Moreover, the court reasoned that in light of the multi-year earnout provision involved in the LLC agreement at issue–that was never signed, the exception to the statute of frauds for partial perfomance did not apply. See generally Section 2714(a) of Title 6 of the Delaware Code (requiring signed writing for an agreement that will not be performed within the space of a year)
SUPPLEMENT: Professor Larry Ribstein has a scholarly analysis here of the decision and a broader discussion of oral LLC agreements, with reference to his prior treatment of the topic in his treatises and other articles he has written.