[jase_coop]

Not so great - Seems to require your Twitter followers to associate their Google account on Migrat.us before it's of any use.

[tonfa]

Yeah, and people can already link to their twitter from their profile page. So this shouldn't be needed, a simple crawler should be sufficient.

[patrickaljord]

Scraping might not even be needed given that Google has an API for that http://code.google.com/apis/socialgraph/

[migrochefort]

A crawler offers no warranty that the Twitter username is legit.