I found a website that will send a BB PIN message to any BB for free,
http://184.108.40.206/Web2PinFree.aspx - I am not so sure about this, notice it's an IP address and not a site name! (But http://www.web2pin.com) does work. And a IP address lookup does say it's for web2pin.com (http://whatismyipaddress.com/ip/220.127.116.11)
Anyways, this does work, I tried it sending a "test" message to myself - The message I got was from PIN 4009B44B, I don't know how to look up anything just using a pin, but it does look like it worked.
What I was wanting to do however was just give my pin out, and let anyone from any network, from anywhere beable to send a message, if the message needed to be acted on I could then send a message back...The above service is only about have of what I was looking to do.
I also found that if I add someone to my BBM via a phone number the messages they send to me will show in the BBM app, I just found that interesting, it doesn't help but I did think it was interesting :-)
IF I try to add someone by email address, and they don't have a black berry, it will send an email that says you don't have the required software on your device. So I don't know how email addresses would really work using BBM
I just find it interesting. It would be nice if Blackberry would open up the messenger so people on other networks could contact a BB user.