I don't see how it is... It is just a different server-side software. "Mod" implies something that changes the core mechanics/adds new blocks. As an intermediate plugin developer, you should know this is not possible with bukkit and therefore I'd say no.
ZanderMan9 MCMastery CraftBukkit would be considered a server-side modification. Bukkit is an API. Mod (Modification) implies something was changed, and considering CraftBukkit vs the Vanilla server, there is a huge change. Craftbukkit could be considered a mod, yes.
"mod" is short for "modification"; I'd call a mod a change to the original code of a game, in which case Bukkit CraftBukkit is one. Edit: As stated by a number of people, CraftBukkit would be a mod, Bukkit is an API
Bukkit is an API. CraftBukkit is a vanilla server wrapper which allows access to the Minecraft Internals via the Bukkit API. Craftbukkit can be classified as a mod, but is more along the lines of a wrapper.
Goblom dsouzamatt ZanderMan9 MCMastery http://wiki.bukkit.org/FAQ Gonna just put out there, wiki says its a mod
http://wiki.bukkit.org/FAQ#What_is_the_difference_between_Bukkit_and_CraftBukkit.3F Bukkit is not a mod; it is an API. It does not include any code references to the official server released by Mojang. CraftBukkit is a mod of the Minecraft Server. It modifies the official server to enable the use of the previously mentioned API by plugin developers.
You're right. From the wiki: As you've pointed out, it's import not to be confused between Bukkit, an API and CraftBukkit, a mod.
Wolvereness Was referring to the person saying that CraftBukkit is more a "wrapper" when I pointed out that wiki reference.
(other way around) bukkit is the wrapper, craftbukkit the server Mod is basically "Modification" and since craftbukkit is a modification of the vanilla server it can be called a mod.
Even more informational, Bukkit is an API; CraftBukkit is a modification to the vanilla server which implements the Bukkit API.