Just to add my 2p - I used to use a Dension unit (ICE>Link Plus) and a Brodit mount, attached to my Chorus HU. It worked well and the hardest part was removing the HU - once I figured out which way the keys have to go it was a piece of cake!
The Dension unit has a small wiring adapter - you unplug the main wiring from the back of the HU and plug in the Dension adapter. The original wiring then plugs in to the other end of the adapter.
There is a lone black wire on the Dension loom which needs to be touching the HU metal case for the unit to power up. The adapter wiring then connects on to the Link itself - a small black, flattish gadget. You then route the wire from this to where you want to mount the iPod. If in the glove box, drill a small hole and pass the cable through to the Link (If you try the other way you end up with a bigger hole for the iPod dock adapter to go through...)
Once you have got this connected together, you need to download the configuration file from Dension onto your iPod - it looks like either a .exe file OR a .zip archive (If you use a Mac, get the .zip file). You expand these and import them in to iTunes. You update your iPod and note where the config files go - there is one called 'start update' (or some such). When you get back to your car, start playing the 'start update' file and plug the iPod in to the dock connector immediately. The display on the iPod will tell you what is going on - basically you are flashing the Link with the right configuration info for your HU. The process takes a few minutes, but is not at all painful!
When done, you can then control the iPod from the HU. CD buttons 1-5 relate to the first five play lists on the iPod, so get these set as you want. CD button 6 switches you to the main menu on the iPod display - in there you can opt to use the iPod controls, which is far more intuitive, IMO. To change between options whilst in the Dension menu you need to use the HU and FFwd/RWnd buttons, etc.
Dension have been pretty poor at keeping their customers informed - they have also now removed their support forums - head over to
www.hackmycar.com or
www.ipodmycar.com for more support. If you are needing the older config and installation files, check out
www.halmaclean.co.uk - on the left hand side you'll see all the Dension files I managed to collect.
When using the Dension, the track counter didn't work as I wanted it - it would either not increment at all, or stick on 99. I also couldn't get track information on the HU with the version I was using (later versions may be better). The iPod display was better for me, in that respect, and having it mounted on the bar next to the gear stick made it very accessible - looked good, too!
I also have a factory fitted phone kit, and the Dension worked well with this - muting when calls were made or received, etc.
However, whilst I was happy with the Dension - sound was great, etc - I wanted a better HU interface. I also wanted a Sat Nav unit and was given a decent Alpine system for my birthday - with an iPod adapter as well. The Alpine system is so much better than the Dension in terms of the display on the HU. I don't need to use the iPod display at all and I now have the iPod in my glove box. The only downside of the Alpine unit is that I can't find a way of connecting the phone kit...
If Audi are basically supplying a Dension unit then you can be sure it will be a pretty good experience and fit well with all the other electronics in the car. However, the firmware needs to be good to display track info on any Audi HU, and this could well have been improved in the year I have not been using Dension. I hope it has.
I'd be really interested in how this all pans out. Tomorrow I am getting my new(er) A3 with a Bose system in it, and I'll want to move the Alpine HU and iPod adapter in to that car too. If it proves too tricky then I'll use my Dension again for a while, but ultimately it would have to have had a substantial upgrade for me to want to change back to Dension from the Alpine (plus, of course, the Alpine does Sat Nav...).
Phew! Sorry for the long post - hope it helps someone!