This is a few years old and leaves out 6LoWPAN[1], which wasn't yet commercially viable. 6LoWPAN is based on the same 802.15.4 hardware that ZigBee uses, but it has two significant advantages over ZigBee. First, it is TCP/IP that works on microcontrollers, so embedded devices running the protocol become first-class members of the internet with the addition of a very inexpensive router[2] to the network. This means that sensor nodes and embedded devices can seamlessly interoperate with traditional servers in a distributed computing environment and many programming techniques can be directly adapted.

Second, 6LoWPAN can be configured so that all nodes involved can sleep, whereas ZigBee requires always-on routing nodes in order to produce a true mesh. This means it isn't possible to use ZigBee to construct a mesh out of fungible battery-powered devices, which is a big problem for many applications.

If this interests you, there are a couple of very capable chips that have been released recently that are ideal for use with 6LoWPAN, namely TI's CC2538 [3] and Atmel's SAM R21 [4]. They both are supported by Contiki OS[5], which provides network stacks for extremely resource-constrained devices. It has been under development for ~10 years at this point as an open source academic/hobby project but in the last couple of years it has become significantly more professional and it is now used in many commercial applications. In addition, its core architects have launched a company called Thingsquare[6] based on Contiki which aims to be Heroku for low-powered wireless devices.

[1] IPv6 over Low power Wireless Personal Area Networks

[2] http://redwire.myshopify.com/collections/frontpage/products/...

[3] http://www.ti.com/product/cc2538

[4] http://www.atmel.com/tools/atsamr21-xpro.aspx?tab=devices

[5] http://contiki-os.org/

[6] http://thingsquare.com/

[7] If you want some CC2538-based open hardware: http://www.openmote.com/