Re: Dogpile.com
dogpile is just a meta-search engine and does not provide the sophistication of a good search algorithm like google. It simply portends to be an aggregator of search results from various other search engines... and perhaps, it does a good job at that.
The thing is, over the past 4 - 6 years, I haven't exactly felt the need to complement google with other search engines. Pretty much anything I'm looking for is available through google or it's various channels like images, scholar, blog search etc. - I compared results I got from msn with google a couple of years ago, and concluded that google had more relevant ones across a variety of queries. So I'm pretty satisfied with google overall.
This is not to say that google is be-all and end-all. There still are specific sites that google doesn't/can't index due to restricted access etc., so I have to individually search them myself, but I'm sure sooner or later, there'd be a mashup search for those types of requests.