This arguement (irreducible complexity) always truck me as funny, considering:
1 - Really... Going to rest the whole of you argument of an intelligent designer on the spinning tail of a bacteria? Okay...
2 - Google it. Its been thoroughly dismantled by people in the field. The only people still clinging to this idea are religious fundamentalist.
The tail didnt occur simultaneously, the "argument" is that if you take any one piece of the tail, it ceases to work. But that doesnt mean it had to form spontaneously, it is the more complex form of a previously simpler tail. Thats all.