Is there any requirement that vesting be shown on a participant's annual benefit statement, or is it enough to show the total accrued benefit before vesting?

I believe the statement required under ERISA should state the vesting percent, and if the EE is not currently vested, include the date on which vesting will first occur.

I agree with pax if there is a request for a statement, but I don't think there is a requirement to issue "an annual benefit statement" in the first place, without a request, so I would think you could issue statements without vesting (if for some reason you wanted to-I don't think it's wise), but would have to provide the vesting upon request.

Thanks, Andy. I agree.

Upon request, the participant must be given both the total accrued benefit and the nonforfeitable benefit, but no more than once a year.

That looks correct to me, but there may be another issue.
If the plan sponsor distributes a statement that has not been "requested" and it does not have all the ERISA-required items (such as the potential vesting date for those not yet vested), then the sponsor is still subject to the employee request.