If I want to add bluetooth capability (to connect my iPhone), to my 2003 L322 V8 Vogue, what do I need to buy?
Is it as easy as finding the bluetooth ECU/Module and plugging it in?

I'd like to know this too

Nope, you have to replace the Telephone module TCU (if you have one) with a BMW ULF unit (get the newest one you can that is compatible, anything above 4th gen if I remember correctly), fit a bluetooth antenna and do some re-wiring on the connector. Then you have to set up a process to pair the phone either by a hard wired switch or something like Navcoder. It's not difficult but a bit of a fuss. I've done it in my 02 TD6 but it's never worked properly. It will pair and the phone appears on the centre screen but I've never managed to get it to call or receive or even to sync my phone book. The problem appears to be that the ULFs are too old technology wise to talk to newer phones. Some have got it working, search ULF on the web and it should come up. Fullfatrr have covered it. Oh, and get a ULF that says "MIT SES" as that retains the voice control function. I might have another go at it over Christmas now you've reminded me.

Ok, it might be better to fit an aftermarket bluetooth kit then. Thanks for the advice.

Parrot thingy works well with I phone, but trying to identify phone book whilst driving is neither easy nor safe!

Thanks, I'll have a look at that one. I have fitted a number of different Bluetooth units to my cars over the years but have not found one that has had great quality. That said, I don't think I have tried a "Parrot" version....

I have a parrot kit in the L322 works very well....

That's not new, long John Silver had a Parrot.