"The grinder is an integral, necessary part of making good espresso in the home.
... a quality grinder to freshly grind the coffee to the very precise particle sizes necessary to good extraction. Often, the grinder is the rock star of their little espresso show."
I've often said that I can make a better shot of espresso with a $200 espresso machine and a $400 grinder than I can with a $2,000 espresso machine and no grinder (or a blade grinder)... and it's absolutely true."
[Later added: a good article on the size to grind for espresso, for anyone using a manual grinder or a cheap blade grinder: http://www.espressopeople.com/guides/grinders/grinderjob)