Have you had problems getting your posts indexed on e.g. Technorati? If you normally use Ping-o-Matic to "ping" services such as Technorati's (i.e. to tell them your blog's been updated and ask them to revisit your blog to reindex it), your problems could stem from Ping-o-Matic having suffered outages lately; it was even completely offline recently.
While it's now back online and work is continuing on Ping-o-Matic, Technorati have asked bloggers to ping them direct too even if you use other methods like Ping-o-Matic. (You can automate direct pinging of Technorati, so that a ping goes straight to Technorati as soon as you publish a post, if you use certain popular platforms. Here are Technorati's instructions for: b2, Blogger, Ecto, MarsEdit, Movable Type, Nucleus, Radio Userland, Typepad and Wordpress. Or after you login to Technorati you can click Update Ping against the relevant blog direct from their ping page, see this post.)
Best do that too for other services like Icerocket (their ping page). Technorati's helpful instructions for automating pings should work for other search engines too though obviously you'll need to tick a different box or enter a different ping URL for each search engine.
For an interesting overview of how some key blogosphere search engines deal with pings and output their search results, see Niall Kennedy's post.
Technorati Tags: Blog, blogs, blogging, ping, pings, Ping-o-Matic, search engines, Technorati, Blogger, b2, Ecto, Improbulus, A Consuming Experience, Consuming Experience