Using PostgreSQL for full text search is a bad idea. There is no native support for exact phrase searching "like this;" there are some hacky workarounds but you lose stemming and have to do a scan (http://stackoverflow.com/questions/1489617/how-do-you-do-phr...).
High quality, world class text search is a basic prerequisite for a production web app these days (if your app needs search at all). The idea of keeping your database and search engine data in one silo is really beautiful, conceptually, but at the moment it is better for your users if you swallow the complexity of maintaining a parallel, dedicated full text search index (e.g. like Lucene) alongside your regular db. Relying on postgres for full text search is a three quarters solution, and if you believed in three quarter solutions you would not be using postgres in the first place.
Just my .02.