If you want to play on my mc server, you should NOT UPDATE YOUR MINECRAFT TO 1.8 YET!
bukkit needs some time to be updated to 1.8 and before it has updated, you shoudn't update to 1.8 if you want to play on our server.
it usually takes about a week for bukkit to update, but because some major updates, and possible bug fixes, it may take a week or two.