Solr: http://lucene.apache.org/solr/features.html
ElasticSearch: http://www.elasticsearch.com/
Both have HTTP-based interfaces, so all you'd need from Go really are
the http and json or xml packages.
Hope that helps.
Josh
The index/suffixarray package could be useful: "The suffixarray
package implements substring search in logarithmic time using an in-
memory suffix array." [1]
You might also want to take a look at godoc sources, it implements
full-text search of the Go source tree. The relevant file is index.go
[2]
[1] http://golang.org/pkg/index/suffixarray/
[2] http://golang.org/src/cmd/godoc/index.go