Good writeup on ipod connection hack FYI
 

im assuming this would also work for listening to music off an iPhone?

You bet, that is what I am using. The iphone has some gsm interference on any connection to the radio (direct, fm transmitter, etc.). But the sound is perfect other than that.

Also what I did is use a $15 ($19?) attachment made by Seidio that has a button and microphone (similar to the iphone's earphones). So you can click to pause, double click to go to the next song, or if someone is calling single click to pause the music and talk to them. Works slick and saves you having to unplug the iphone and put the caller on speaker phone (while driving I find it easier to click a physical button than unlock the phone and push speaker etc which makes you look away from the road a long time).

http://www.seidioonline.com/index.asp?PageAction=VIEWPROD&ProdID=300

Also Proclip makes iphone holders specific for the boxster.

I thought about a more elegant docking/charging solution similar to this (but I wouldn't drill holes in my dash):

http://www.youtube.com/watch?v=ggHqdx5drko

but haven't found the time or energy.

I used: $5 rca to headphone jack cable from china mart + $7? extension cable so more freedom of movement (headphone jack to headphone jack cable) + Seidio adapter $20 = $32 No docking solution yet as I just set it in the cubbyhole in the center dash.