Apple doesn't seem to care much for " tasks " rumor has it that steve Jobs lives out of the apple mail program .
Recently there's been a slew of GTD apps for the Mac coming out , some of them are very good ..all from 3rd parties . Just to name a few there's iGTD , OmniFocus , TaskPaper and a new one in alpha right now called " things"
I don't think think iCal tasks even sync with the iPhone ?
You are correct that iCal Tasks do not sync to the iPhone unless they are attached to a specific dated entry.
I think you are right that Jobs lives out of the Mail program and the relationship between Macs and the iPhone is exactly that. To get material (other than calendar events, web links and contacts) onto the phone requires that you email it from your Mac to your iPhone.
The link goes in the other direction as well. To get a Note out of your iPhone to your Mac requires that you email it.
Basically, the Mac-iPhone setup works using two paired programs. Email and Notes. One sends information easily from the Mac to the phone and the other sends information easily in the other direction.
Mail is a very robust program and allows you to view PDFs, Spreadsheets, etc.
I've been working my GTD system this way for a couple of weeks now and once the oddness of it wore off, it does work rather well.