On Wed, 31 Aug 2011, Francesco Poli wrote:
"3. All advertising materials (including web pages) mentioning features or use of this software, or software that uses this software, must display the following acknowledgment: "This product uses software developed by Spread Concepts LLC for use in the Spread toolkit. For more information about Spread see http://www.spread.org"";What you quoted looks like an Obnoxious Advertising Clause (OAC), a GPL-incompatible restriction, but one that has traditionally been accepted by the Debian Project as compliant with the DFSG (even though recommended against), AFAICT.
Unlike the original BSD 4 clause license this adds "or software that uses this software". If I interpret this broadly (all software that uses this software must display the sentence) it's non-free, since it imposes conditions on non-derived software that happens to use it. Even if I interpret it narrowly (all advertising materials mentioning software that uses this software, must display the sentence) it imposes conditions on advertising for non-derived software. If I interpret the addition as meaning "derived works" the license is free but the wording is redundant.