As name suggests Wireless LANs were developed to replace ethernet. Hence a lot of the ideas like frame format, CSMA, parts of MAC protocol...were borrowed from ethernet. There are many flavours to Wireless LANs(802.11). 802.11b operates in 2.4 GHz band and can achieve data rates of 11Mbps. Texas Instruments uses its propreitory PBCC to bump this data rate to 22Mbps. 802.11a operates at 5 GHz to achieve data rates of 54Mbps. 802.11a uses OFDM(Orthogonal Frequency Division Multiplexing). 802.11g operates in same frequency band as 802.11b and achieves data rates of 54Mbps. There are others being developed like 802.11i(enhanced security), 802.11n(higher data rates).
802.11 is a hit. Hot-spots where one can use their laptops to connect to the internet using 802.11 are emerging everywhere. There are a numerous number of companies thriving in 802.11. some are on the chip side and some are on the network deployment side. Leading chip companies are Broadcomm, Texas Instruments, Intersil, Atheros. Laptops are now being shipped with built-in 802.11 chips, Intel pushed a lot for this to happen. Intel has integrated 802.11 cores into some of its Processors. 802.11 was one of the driving forces behind laptops to overtake the sales of desktops. 802.11 has come a long way from 1999 when it was relatively unknown to its current household name status.
Q&A:
What were the reasons for the success of 802.11?
backwards compatibility, using a standard to ensure interoperability, AP and adapter prices have gone down ten fold from $1000 range to $100 range because of a free-fall of chip prices, long range, Plug & Play among others.
What are some of the problems with 802.11?
Weak security, not suitable for multimedia and streaming video, wireless LAN switching technology is immature, ...