Q:

Does a Wireshark implementation exist for iPhone 4? 

Does a Wireshark implementation exist for iPhone 4?  I recently felt a need to have some tools with me at all times. 

A:

If you have a jail broken iPhone you can ssh into it and install tcpdump.  Tcpdump is a command line program that wireshark is indirectly built off of. 

A:

There's no WireShark app for iPhone no but there are a few Network Diagnostics tools which may do what you need since you don't state exactly what you want to do.   Take a look at Network Diagnostics Utility Pro which is $4.99 and might cover your requirements. 