Lol, they might have some "hype" value, or some ppl might see them as the next big thing, but IMO they have about regfee value.
Depends on what you class as "highly valuable" to be. L-L-L.com names usually start from Mid $xx all the way up to the $x,xxx range, depending on the letter combo or if it's a word. L-L-L-L.com are totally worthless IMO, unless it's something like P-O-R-N.com, C-A-S-H.com, etc.
They do have a lot of value overall, L-L-L.com are increasing in value fast and their sales have been high. However the rest do not have much value at all, unless they are good words.