There's a lively debate happening at the Gottesdienst blog. It's scholarly but thorough.
If you check it out, read the posts in this order:
For my own part, I believe the Scriptural and Lutheran position is that the Words of Jesus bring about His presence, and that presence endures until everything is consumed. And my practice confesses that. Because Receptionism is nearly as prevalent as it is false, I genuflect during the consecration. And because any talk of the end of Christ's presence in the Supper is speculative at best, and an impious denial that the Word of the Lord endures forever at worst, I consume everything that has been consecrated.
If you're not getting enough of this conversation in Bible Class on Sunday mornings (or if you're note getting any of it), go read what these other faithful Lutheran pastors have to say on the issue and come back and discuss it here.