Do MacBooks go out of date quickly like iPhones?

I have an iPhone 5 and even though I only have it about 18 months it's already out of date!

I'm interested in buying a MacBook Air but not sure whether or not to buy one now. When was the latest model released?

Also is there another model expected to be released soon and if so would they go out of date quickly? Generally how often are they updated and are there many changed between each version?

Not at all! I have had my MacBook Pro for over 3 years now. It felt outdated because of SPECS. So what I did is switch to a SSD and double my RAM capacity. Now it feels like a new computer since it can handle more tasks (RAM) and access stored data much faster, such as opening an installed application (SSD). Now its battery is degrading slowly and I can only use it for 2 hours continuously with a full charge whereas it used to be 3-4 hours in the past. I'm not a fan of the Air though. Pro version is better for long term.

If you are looking for a general productivity laptop, Macs are the absolute best. Their OS is much more stable and virus free than windows, plus it has a better UI in my opinion. PC users use the generic "It can't play games" argument, but what they don't realize is it is very reliable for people who want to browse the web and use a couple productivity apps (MS Office, Adobe software) instead of using it as a gaming machine. If you want a high performance laptop, go for a PC, if you are just an average computer user, go for a Mac.

"Out-of-date" is a matter of opinion. Heck, 30% of the PC geeks are still using Windows XP. Is that about ten years out-of-date? Any computer you buy will be laughed at by someone six months later who buys the newest rig.

New models can come after 3 months or not for a year. Apple dates the models by thirds of the year, such as "Early", Mid" or "Late". Here is how the Air has been update:

Early 2008
Late 2008
Mid 2009
Late 2010
Mid 2011
Mid 2012
Mid 2013
Early 2014

If you would get an ulcer from shame by seeing a new model released a month after you buy one, wait. A new model could be released next month or in three months.

Playing with games actually is a test of graphics much more than any other aspect of a computer. Since most games are for Windows only, PC makers must bear this in mind. More than half the PCs sold are used mostly for playing with games. If a PC brand is poor playing games, it won't survive in the market. There are just too many brands competing.

BTW, here is a test of "gaming" with MacBook Pro 15-inch (Macs with screens below 15-inch are NOT to be considered at all for playing with games)…

http://bestgaming.newlaptop2014.com/15/15-retina-macbook-pro-nvidia-750m-late-2013-gaming-test-crysis-3.html

It's a shame that the teenage game-boyz rule these forums and judge "performance" solely on playing. Some of us do work, and for my work, Mac system is by far the best.