Ads not showing

Hi guys,
I moved from Yahoo to Google adwords a few days ago (at the same time, I dropped adsense; this makes me think that there’s really no way to avoid Google), because I think their management is much clearer.
However my ads do not show; yeah keywords are active, the text for the ads is all nice all optimized, no ad has been rejected, and this is not a problem of budget since I throw min $100 per campaign. However the keywords traffic estimator gives me stats which indicate that I should receive a lot of clicks (and considering the situation I really should), and no bad message indicating that I should optimize the text or bid higher.
Question: any good reason ? Is there some kind of pre-approval for the ads (I know the is the case for the content network but shouldn’t the process, even if damped, start almost-instantly ?)

Original post by eldel