Already knew this (checked before commenting to make sure they didn't have it and found that out). Although using regex might make it a lot more server intensive - even though, the majority of people wouldn't use it besides "nerds" like us
I think it would be difficult to calculate a good ranking when using trigrams for regex-search (as in the link). As far as I know besides pagerank you have to rely on a term-based ranking function e.g. bm25 http://en.wikipedia.org/wiki/Okapi_BM25.
