389.42 ppm
(From CO2 Now, an advocacy group, but they appear to get their data from the Mauna Loa Observatory, so we can establish sufficient credibility.)
Worse than even I expected. Remember the good old days when An Inconvenient Truth had just been released and CO2 was still at 380 ppm?
Nothing in science changes quite as fast as climatology data these days. My school chemistry handouts are outdated only in that sense; they keep saying that CO2 is at 350 ppm.
ClimateSight 
Nice blog! Check out this one too:
helpcooltheearth.wordpress.com
CO2 Now is a fine website. I tend to use it for the purpose suggested by its name, let’s see what the CO2 level is right now. The previous posting for the month of May was ~390 ppm and I had your reaction, “what do you mean its that high?” And I went of to more authoritative websites to vet their data and found that it was true and correct. It is summer and the level will fall slightly for a time before increasing even more, as we all know. Recently I was reading a paper by David Archer on the atmospheric lifetime of CO2 and had much the same reaction as I did to the May levels.
I am tempted to do some research on the question of what the rate of increase has looked like over the past fifty years.
Any bets on how long it will take for a denier to get a hold of the CO2 Now website and say, “Oh look, there’s less CO2 in July than there was in June, carbon emissions are going down, scientists are all evil communists?”