Hey, I signed up for burst 2 days ago and had my banners up yesterday. However, just like before (which is the reason i never participated in these programs) my impressions seem much much lower than my pageviews and even unique visits. My Urchin stats (Urchin is supposed to be great) say i got 7,000 unique visitors yesterday and 35,000 pageviews. Then how could i only get 1,000 paid banner impressions. Im pretty sure i have the banners on all the sections of the site.
I think burst is a reputable company and wouldn't cheat you out of your dollar. You may have a lot of internation traffic, or since you just placed it up yesterday the code/ads, hasn't appear on every page yet...etc. Who knows...just guessing.