On the SitePoint PHP blog Bruno Skvorc has a new article with a few of the reasons why to choose PHP over other alternatives. It's a quick post with only a few points, but it's interesting for its choices of when not to use PHP.
It’s a popular question. Why indeed should one pick PHP over one of the alternatives? After all, PHP has often been dismissed as a unusable and badly designed language. Why would anyone choose it, when starting a project from scratch? Instead of listing the reasons why people do choose it (mostly widespread availability), let’s instead focus on why people should choose it. We can’t talk about that, however, without first mentioning why they shouldn’t.
Among their suggestions of when not to use PHP are things like building command line applications and "just because it's there" on your shared hosting. There's a section near the end of the article that talks about some of the work that's been done to try to dispel the "bad press" PHP has gotten and how other languages (his illustration is Javascript) have the same kind of taunting and nitpicking happening as well.