When I first started developing with the Microchip MRF24J40 802.15.4 Radio, I purchased Microchip's Zena Wireless Adapter and downloaded a copy of the Wireless Development Studio. It has been adequate for diagnosing issues at the raw MAC layer, but less useful when it has come to protocols such as 6LoWPAN with IPv6 header compression.
Wireshark is the de facto standard for analysing IP based networks and has support to decode 802.15.4 packets. The problem is finding suitable hardware to capture the 802.15.4 packets and pass them to Wirehark for decoding and display. Much of the existing hardware encapsulates the packets and sends them to Wireshark over an ethernet or TCP/IP connection.
The guys over at Freaklabs have a WSBridge open source application that acts as a bridge between Chibi/chibiArduino and Wireshark. It receives raw packets on a serial port and creates a Pipe to feed the captured packets into Wireshark.