Google Blog Search has started offering a ping service, where you can submit your updated blogger address via this link. Google will crawl your site sometime in the future (depending on luck).
Although Google also monitors other ping services (which means that even if you don't ping your blog to Google Blog Search directly, it might still be included in Google Blog Search), pinging Google directly can shorten the interval between updates for when Google crawls your blog. At least, that's what Google claims.
For more detailed information, you can visit the Google Blog Search Pinging Service FAQ or Got blog? Will ping.