The Motorola headsets and carkits are having a delay issue with opening the "SCO link (Audio link)" with the iPhone. The SCO link should open once a call is placed or received, sadly the phone isn't properly updating the headset as to the call status. The iPhone use the Bluetooth handsfree profile version 1.5, most older Motorola's use version 1.0.
Don't get this confused with the Bluetooth core versions 1.0, 1.1, 1.2, 2.0 and the soon to be 2.1
The Handsfree profile is a sub profile that is used in the core spec. Such as GAP, BPP, BIP, OBEX, PIM, OBEX, FTP, DUN and A2DP.
The Apple Bluetooth headset (HFP 1.5) has some backwards compatibility issues with older phones as well (HFP 1.0).
This isn't technically a failure of the phone. It's the Bluetooth chipset which is used in the phone/headset. Just be glad we aren't all having eSCO issues like the new PDA/Smartphone's were having, 4 firmware updates later, what a headache.
On a side note, those of you having this issue with the Motorola's, did you buy your units in the store or online. About 8 months ago there was a huge issue with Motorola headsets (HS850, H500, H700 and some car kits) that were duped by some company in Taiwan or Thailand.
I have a H700 and my audio delay is only 2-3 seconds.