[canweriotnow]

No, no. In fact, last time I checked, the lein docs warn about using brew because the versions may be out of date.

[danneu]

From its README:

    > If your preferred package manager has a relatively 
    > recent version of Leiningen, try that first. 
    > Otherwise you can install by hand:

It's kept up to date: https://github.com/mxcl/homebrew/blob/master/Library/Formula...