For what the MacBook Air is made for, you don't really need the extra 2 gigs. I bought a base 11" yesterday after some extensive research and believe me I was not disappointed a bit after playing around with it for a while. No matter what I throw at it it remains snappy. I am a videographer looking for a more portable solution to my 2009 MacBook Pro 13" (which I sold to get the air), and believe me Final Cut runs like butter on the Air! HD videos from the web run great as well. Microsoft Office 2011 just zooms. Heck, you can even play COD Modern Warfare 2 on it, just search for videos on YouTube for evidence.
And you know what else, I've had multiple programs running including memory hogs like Safari and never did my memory run out. I was monitoring it with Activity Monitor.
Having an SSD drive really helps in this regard so don't get put off by the 2 gigs. It is hard to teach an old dog new tricks. I myself wanted the 4 gig version, believing in what I learned before: more memory is better. man, was I wrong on this one.