So when the whole iTunes/iPhone/Ringtones thing came out, I decided to ignore iTunes 7.4.x until:
a) There was something I needed b) I was sure that it wouldn’t screw up my customized iPhone
So I went to Software Update’s menu and chose Update → Ignore Update which warned me thusly:

However, when I ran iTunes again, it told me:

So I guess Software Updates and iTunes don’t talk to one another. Note that there is no option to have iTunes stop annoying you about this. I presume that if I say no to downloading it “now” it may ask me again.
Since I had rebuffed it twice, I wondered what it would take if I decided that I did want to download iTunes. So I went back to Software Updates:

Now I realize that to those of you who are familiar with Macs, this alert panel doesn’t surprise you much. It’s what you expect, but notice that it reminds me that I have told Software Updates to ignore some updates. If I had gone to Software Updates because I heard there was a new version of iTunes, it wants me to know that I’ve hidden some updates there.
After that it doesn’t give much control. It does not:
1) Show me which updates I’ve ignored
or
2) Allow me to choose specific ignored updates to now apply
If I choose “Reset Ignored Updates” it will show me all of them.
One curious thing. The first warning panel above says:
You will no longer be notified of new version of this update.
However, I had chosen “Ignore” for the Apple Keyboard Software 1.1, and version 1.2 did appear in my Software Updates, so at least in this one little example it seems that Software Update says one thing and does something else. However I’d have to test it again to be more conclusive.
Last Thought: Seriously, what’s gotten into Apple’s release notes lately? I’ve seen more words on a fortune cookie.