here’s a list of most of the vendors selling IEEE 802.15.4 modules (PC with chip, antenna, MAC/PHY microprocessor, and ZigBee processor). Omitted are some that are not intending ZigBee compliance. Some have only 1mW transmitters, other have up to 100mW. These are all (except ZMD) 2.4GHz modules as this works worldwide. Prices @1ea run from $20 to $75 or more.
This is not a list of chip vendors such as TI/Chipcon or Freescale.
Atmel/Crossbow (just 1mW. ZigBee stack source is?)
Clarity - ZMD
Crossbow (ZigBee certification planned?)
Eazix (pre-production)
Ember ($$$)
Helicomm (Silicon Labs reseller)
Jennic (oddball microprocessor)
LSR (Unique in having 100mW)
MaxStream (now owned by Digi) - popular, low cost
Meshnetics (Moscow?)
MoteIV (ZigBee planned?)
OKI Semiconductor - Digikey sells. Low cost
Panasonic - ditto OKI
Radio Pulse (?)
Silicon Labs
Talon (San Diego) - Specialized. ZMD
ZMD (about the only 900MHz product)