yes, even the worst 4 letter random domain will mean something to somebody, it will just be harder to sell (that person might not want it!).
My order of value would be:
1) LLLL word (probably any, just because it will be only 4 letters long) 2) LLLL common acronym 3) LLLL 'non-dictionary' word (something you can pronounce) 4) LLLL looks good (i.e. ssss) 5) LLLL Random good letters 6) LLLL Random 'Junk' letters
?) LLLL Wild card - Company acronym, anywhere from first to last (and probably is 5 until the company is 'born') - other thing is the company might not like its acronym! eg: Computer Recyling Associated Partners (just made that up to illustrate, NP$ if registered ) - so it wouldn't be interested.
I think that they will run out in the next 3 years and that is when they should have a nice increase in value. The are around 450 thousand four letter .coms and I think that somewhere between 90-95% have been taken.
I like 4 letter fictional words like VURG. I think that the ones that nobody has taken are unique (or somebody would have taken them) short words that have great brandable potential.
Another category of four letter domain names is the rhyming domain names.
eg. TPVD.COM
Some people will pay a premium.
I keep watching the prices that people are buying 4 letter .COMs on eBay and there are a few that sell well (over reg price) but most don't. I think this will be different in two years time.