Here is my conundrum: I've been using google code forever. However, as more potential employers are interested in github profiles, I would be presenting one with a very recent creation date (on the left side of the profile). Unfortunately this could provide the wrong impression (ie. that I just started to program very recently).
An employer may look at the dates commits were made, and they might suspect something. You could always provide a link to your past work in your github profile.
it's a reasonable and probably common situation. it may be better to just be truthful and refer to your actual prior projects, wherever they are. if the potential employers can't understand this, do you really want to work for them?