I've been out of the loop on ZigBee for a while now. Who has the most mature Zigbee stack? Is it Microchip, Chipcon, or Atmel?
Are there RF modules down to less than US$10 yet?
I recall there was some licensing issues with certain stacks a while back...
(This question was originally asked in 2009. As of 2012, I don't think Ember is a leading stack anymore. It seems that Texas Instruments has become the dominant chipset/stack... Although, their stack does seem to be locked to using IAR's terrible IDE which would make me think twice about using it.)
I've done some work with the TI stack. It's... ok I guess. The IDE limitation makes it pretty awful, and there are some rough edges. Documentation isn't all that great, and when you hit a certain level you run into a closed-source driver module (this might be a common limitation among vendors, haven't done enough with them all to know offhand.) Still, after having built a proof-of-concept demo with the TI stack, I'm still looking for alternatives.
Saw a bunch of them at ESC and CES. For reference, some options (no particular endorsement either way, in alphabetical order)
Any other suggestions/alternatives would be welcome.