That was requested by users in Y!360 an implemented as local feature, but now Google release global Google Blog Search that allows to search all the blogs which feeds can be indexed. As it mentioned in Google Blogsearch Help - Blog Search will respect robots.txt files and INDEX, NOFOLLOW meta tags. What's more interesting - Google allows already known commands like:

• link:
• site:
• intitle:

also they added a few new ones that might be helpful:

• inblogtitle:
• inposttitle:
• inpostauthor:
• blogurl:

Another quite useful feature that you can search blogs in 35 languages - go multi-lingual!