Please do see http://news.ycombinator.com/item?id=498699 (memcachedb != LightCloud). memcachedb should be compared with Tokyo Tyrant and not LightCloud.

And if you liked, you could extend LightCloud with memcachedb support (which we also had at one point and ran it in production [see my posts on memcachedb mailing list for proof]), but really, when it comes to key-value databases, it's really hard to beat Tokyo Tyrant, which is the fastest and most feature complete key-value database out there (IMO and I have looked at most of the popular solutions).