Bluetooth enabled car stereo

I've seen an increase of car stereos with the auxillary input for your ipod.. even new cars come with it..but I just came accross the sony MEX-BT2500 which has bluetooth connectivity in addition to the aux input.. which is pretty cool if you carry tunes on your music phones or smart phones and use it as your ipod.. with memory increasing on cell phones (the nokia n91 has 4GB-8GB) more and more people are going this route vs carrying an ipod too.. but this is also why the iphone is coming out right?.. most of the time you have to buy a special adapter or cable to be able to listen to your tunes from your "music phone or smart phone" ..this overcomes that issue..at least while playing in the car.. it also allows you to do hands-free calling but its limitted to incoming calls and only redialing the last number dialed..(what is that about?) I would have to agree with this cnet review that apart from music streaming the "principle purpose of the system, therefore, is to accept incoming calls"..a feature that limits the full usage of bluetooth connecvity