Multiple Bluetooth devices?
 

I was wondering if I could hook up a bluetooth mouse, keyboard, and bluetooth 56k model all at the same time?

No sorry. You can have multiple phones paired at once but only one active device connected at a time. Keep in mind this is in regards to the "Nokia" software. Whether or not third party developers can achieve this is unknown.

I have succeeded.
 

I had in one time an open GPRS internet connection through my nokia 6310i and simultaneously transferred data from Bluetooth enabled GPS positioning device. The computing device was a notebook (Sony Vaio Z1)

Phone crash is right. It may have been an older software version, but you can be using bt gprs and also browsing the phone at the same time.

Right, but you can not have more then one active device at a time.

My bluetooth keyboard is a device.
My SonyEricsson P900 is a device.
My bluetooth GPS is a device.

I can use them all at once with no problems. I'm not sure why you bolded device in your post - are you saying you can only have one device of each type active at a time? If you start a bluetooth keyboard daemon on the command line, I'm pretty sure you can start up more than one. You can definitely use multiple bluetooth GPS's, and if you use the command line, you can hookup a couple phones and do GPRS from all of them if you want - you'll need your own load balancing setup for that of course.