John of Freshblog and David Kaspar have pointed out, with the whizzy new Firefox 1.5 upgrade which came out about a week ago (and the Greasemonkey 0.6.4 upgrade which was released soon after), a lot of Greasemonkey user scripts no longer work. (I think it was that as much as Blogger's hiding of the date/time settings which resulted in a problem for some in editing old posts on Blogger).
For those not familiar with Greasemonkey see this post
Unfortunately the Technorati tag creator for multiple word tags Greasemonkey user script for Blogger users is one of the broken ones.
Until it's fixed (cold towel job & all that) I'd suggest you use the Firefox Technorati tag creator bookmarklet (which also supports multiple word tags) - I have to say that that is what I use myself, because you can tweak it quite easily to always output the code for your own blog's "meblogging" tag (e.g. "Improbulus" in my case), for instance - I've explained how even beginners can customise it. (It doesn't work in Internet Explorer, however, as IE won't take long bookmarklets.)
Note: now fixed, see this post.
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