I am not currently a Blackberry owner but I am seriously considering an 8830 or 8330 from Verizon. I want to ask about an obscure concern - can a Pioneer or Alpine head unit, like the Pioneer DEH-P7000BT or the Alpine iDA-X100 read mp3 files off of a Blackberry?

as far as i know the 8300 can be used as a normal memorystick reader on your computer, so my guess is that it can be used on all devices which have an USB connector. but i can't confirm this...

Pioneer is very good quality, alpine has a nice display, both are good, I personally have everything pioneer in my car (head unit, 4 speakers, and sub), the amp is alpine.

Current Blackberry's come with a small amount of FLASH memory and a micro SD card slot. So, I believe the original question is equivalent to whether you can use the SD card as FLASH memory when connected to a computer.

Given that you have to install drivers to access the microSD slot (i.e. not natively supported by the USB bus), I'd say no.

Simple solution is, find a headunit that will take an A2DP input and Bluetooth the audio over. AVRCP support will let you fast forward and rewind right on the headset too.

or what i did is mine, i think its a "dual" has an audio in jack and just run a cable form your BB headphone jack to that.