If you can wait, wait. The difference between the 2010 and 2011 in usage is pretty minor for most everyday usage. I'm a developer who uses the air as my main machine and have hardly noticed a increase in performance between the base 2010 13' and ultimate 2011 13'.
contemplating to upgrade or stay with 2010 macbook air and wait for the 2012 macbook air 11" with ivy bridge?
If the 2010 Macbook Air is enough processing power, then you should stay with it. Its graphics are approximately on par with the 2011 Macbook Air, its processing power is a fair bit worse... and otherwise it's very, very similar.
Do one of the following:
1) Sell your Air now for as much as possible and switch over. This may be more sensible.
2) Keep your Air and see what the next Air has to offer. Remember... we're not guaranteed a refresh in 1 year from now. It could be out in Q4 of 2012 or even Q1 of 2013 (who knows?). Apple is smart about their hardware choices (usually).
Side-note: I hope the next-gen Macbook Airs (particular the 11-inch model) come with better battery life. I'm going to be buying the external battery device that is offered for the Air by some website... alongside the Airport adapter it'll cost me probably $300 once taxes and s&h are all taken into consideration... but it will most definitely be worth it! Extra 10+ hours on the Air = awesome for traveling. Somewhat defeats the purpose of having an ultra thin ultraportable... but it's good in a backpack or in a car (I usually have one or the other when I need battery life on the go).