I use SEF and URL rewrite (the core components) in joomla 1.7 and it works like a charm on the site itself. However, it is not registered by the Xmap sitemap, that still shows 'component/k2/item/'.

The menu items are registered correctly, so I am guessing it is something with K2. And yes, I do have the K2 plugin in Xmap enabled. Doesn't help.

Am I supposed to go with one of the commercial URL rewriters K2 promotes? Help please.

similar problems here where K2 has inserted categories and /item/ and also the articles id number before its title into the url.. terrible terrible SEO especially for a site with indexed pages adding the K2 component.

I have the same problem and have tried all angles...

the only way to get round is to not show ITEMS and attach items to a menu (not an option for me 2 many items).

Let me know if you do find the answer and I will do the same in return.

are there any workaround?

Yes, not a work around but more a temporary solution that helps / works.

You can go to the K2 plugin (for Xmap) and set "Show K2 Items" to "Never", then your categories and items attached to a menu will show but items not. Atleast Google will get it from those pages.