HFS+ allows file names up to 255 characters. OS X uses all of them, you really can name files with up to 255 character names.
The Classic Mac OS does not (yet?) recognize the extra characters, and may chop them off if you look at a long-name file. A future revision (OS 9.1) may change that, or may not.
If you must have longer names, get OS X Public Beta and try it out.