I added google site maps to all four of my blogs tonight. Very easy with a word press plugin. If anyone is interested in how to do it Andre Chaperon has an very clear camtasia tutorial on how to do it.
Apparently it gets google to index your site pretty quickly. 3 of my blogs are relatively new (a month or six weeks or so) even thougth I loaded them with about 50 posts each before I launched them ...they still don't get much traffic compared to my other blog which has been around longer and has been successful in getting backwards links.