Bukkit will create the plugins folder if it doesn't exist. If it's not, my guess is that something is preventing it from starting correctly. Do you have a server log? Take a look in there and see what it says.
Also, how are you starting it and on what operating environment?
Rollback Post to RevisionRollBack
Former Support Guru and bukkit admin, master of the I-have-little-time-so-I-drive-by-post style.
Please don't PM me for help, PM's don't help the community at large as it's not publicly viewable.
Use pastie or pastebin for config files, I do not download them.