There are always tradeoffs between generic and specialized applications, particularly in the area of information processing. The generic applications cover a wider spectrum, but specialized applications excel in their niche – because they have an intimate understanding of the semantics of information in their topics.
In the end, there will always be place for generic search – because it may not be economical to have a vertical search engine for every vertical. However, in major verticals, specialized search engines might take a big bite out of the generic search engines’ market share – including Google’s advertising pie.
More on vertical v generic search at the Read/Write Web and from the Whats New Media Wiki. Previously from WNM: Google vs. Yahoo: homepage vertical search usability