A connection always has two ports. An origin port (here: the one the 
iPod Touch connects from - 50511) and a destination port (here: the 
port RB opens on your machine and the iPod Touch wants to connect to - 
8888).

Given the port number, it appears as if the firewall blocks the 
incoming connection. If you run Leopard and your setup looks exactly 
like the one in the FAQ, there are two possible solutions:

1) Disable the firewall altogether. Since all OS services you run are 
not firewalled by it and you add an exception for the only other 
service you are running to allow everybody to connect to it, the 
difference and security win is zero, but you avoid all the problems 
the Leopard firewall can cause (see 2).

2) Remote Buddy is a code-signed application to ease interaction with 
the Firewall and Keychain and avoid you being annoyed with OS X asking 
for your permissions on each update. If, however, the code signing is 
broken (which can easily happen if f.ex. you use a copy of RB you 
previously used under Tiger), OS X will ignore all exceptions (in the 
Firewall) and permissions (in Keychain) you have set up and block all 
of these accesses. That, of course, won't keep it from still listing 
both permissions and defined exception rules. Solution here is to quit 
Remote Buddy, download a fresh copy of Remote Buddy (with intact code 
signing) and replace your current copy of Remote Buddy with it.

I'd love to add a requester to Remote Buddy that tells you should code 
signing of your copy be broken, but there is no API for application 
programmers to the code signing mechanism of Leopard as far as I know 
(and I did quite a lot of research).

Best regards, 
Felix Schwarz