The 110 "Pocket Instamatic" format was introduced in 1972, and has by all measures been a very successful format. Every major film manufacturer except Ilford made 110 films. Every major camera manufacturer except Nikon made 110 cameras. 

Kodak led the way with a relatively full range of films — black and white (Verichrome Pan), color slides (Ektachrome), and color prints (Kodacolor).

Today, 110 film is being reintroduced by small manufacturers. There are tens of thousands of excellent 110 cameras in existence, and the owners of those cameras can now buy fresh 110 film for their wonderful little machines.

It is entirely possible to make superb photographs with 110 film. There is a widespread misconception that the cartridge causes poor film flatness, but this allegation is unsupported by the facts. The flatness of 110 film is perfectly adequate. A modern 110 film used in a sophisticated camera like the Canon 110, the Kodak 60, or the Minolta and Pentax 110 SLRs, can provide images of exceptional quality.

Kodak's Kodacolor 400 110 film is also excellent, but it is an ISO 400 film packaged in a cartridge that triggers ISO 100 exposure when it's used in sophisticated 110 cameras. This results in gross overexposure, which creates distorted colors and coarse grain. 

When it's used  in a typical thrift shop orphan, most of which expect an ISO 200 film, the variance in exposure is acceptable, and given the wildly variable actual shutter speeds of most cheap cameras, the results have a 50/50 chance of being quite good.

A small supply of reasonably fresh Fujicolor 110 remains available (as of early 2010), but it is dwindling fast. Manufacturing ceased some time in 2004 and existing stocks are past their nominal "process-before" date. Both Agfa and Konica made 110 films and sold them under their own brand names, as well as under a variety of "house brand" labels, and are well worth acquiring and storing in a refrigerator or freezer if you can find them. The Konica films are especially good — Konica's failure to achieve widespread acclaim for the quality of their films is puzzling — but they do not age well, and older stocks should be tested before you use them for important projects..

110 black and white films are slowly making their way into the market, but at the moment (September 2012) they are not regularly available in quantity, and the only way to find them is to use a search engine to locate whatever supplier is currently offering them.

110 cartridges from all manufacturers are sealed in moisture-proof laminated foil wrappers, and can safely be frozen for many years, perhaps even for decades. 

110 films should not be stored unwrapped. Bare cartridges should be put into moisture-proof zip-lock type bags and refrigerated. 

The day will come when 110 film is no longer available, and aficionados would do well to stock up now.