Did you try the eclipse.org page? (community section)
As far as I know, the only struts plugins available for Eclipse 3.1 are commercial ones.
If you have $99 you can buy a licence for Exadel Studio pro which has Struts "nature" available. (And
JSF support if you're interested)
Nitrox is in the same field, does more but costs way more.
If you're looking for free ones: Struts Console (search for james holmes) but that is just tiles and struts-config viewer. So no wizards for with this product.