These kinds of technologies come in two general forms: as replacements for wired links in conventional networks, or as intermediate forms of mobile networking somewhere between the LAN range normally associated with wireless conventional networking and commercial mobile networking technologies. Increasing bandwidth, decreasing cost, and increasing availability are all conspiring to change the faces of networking as we know them.
Point-to-point (also known as "line of sight") wireless links are advancing to the point where they can not only replace conventional electrical wiring (including high-bandwidth coaxial cable) but even replace far higher-bandwidth fiber optic links in some cases. Some companies have built line of sight wireless links with multi-gigabit data rates, which are quite competitive with fiber optic links—particularly in densely populated urban areas where lines of sight may be accessible, but access to fiber optic links are either unavailable or too prohibitively expensive. This technology is really a form of "virtual wiring," rather than providing any kind of mobility, though.
Metropolitan area wireless solutions like Ricochet also offer interesting capabilities to those who roam within their service areas. Although such technologies once operated at cellular modem speeds, many are now available in bandwidths to low-end LAN speeds. They are particularly popular in densely populated urban areas where certain kinds of users—consultants, temporaries, service representatives, and the like—may find easy access to the same network more convenient than joining and leaving networks as they move from one location to the next as part of their work activities.
Cellular and other telephony-based wireless technologies are still available, and still widely used on laptops or hand-held PCs. Though their bandwidth makes them slower than even normal phone links nowadays, for some kinds of users this technology provides much-needed access to email, order forms, corporate databases, and other essential applications and data resources for "road warriors." Though significant increases to bandwidth are unlikely for these kinds of devices (they're pegged to specific transmission frequencies, devices, and usage that doesn't leave much room for improvement), for some users such limited access is clearly preferable to no access. This is particularly true for those who roam outside the reach of faster wireless technologies, and for whom wired connections (or access to other Internet links) may not be possible or practical.