Does it mean that all 4-letter-.com domain names are taken?
However, what has happened with LLLL.com's is that they went very quickly to $xxx but have since dropped considerably so you can acquire LLLL.com's (4 letter.com's) from $15 upwards although if you want a really nice LLLL.com such as Made, Ball etc then those prices are different regardless of it being an LLLL or not.
Just have a look on Domainer forums such as Namepros, DNF, DigitalPoint etc and you can find some really cheap.
Of course domains expire or are sold between owners so getting a 4 letter domain is still possible.
It's not a word but it is easy to say and to remember, and I needed one for a project, so I got it thinking I could reuse it later.