The most trafficked blogs powered by LightPress are those published by the Italian nanopublishing company Blogo, which I helped found last year and later left. The 15 blogs are housed on an old Celeron 900, and backed by a dual-Xeon MySQL server which is mostly sitting idle thanks to our caching module.
In September, the old Celeron served 2.25 million page views, with a peak rate of 250 page views per minute on September 26 at 11:04:00. If you take into account that every page view involves several image hits (~10), at least one adserver hit (hosted on the same machine), and one stats logging hit (same machine, again), all of them served by a fat Apache, LightPress seems to handle itself pretty well under load.