Rakuten has the 2010 Kobato large desktop calendar up for preorder. CLAMP will illustrate the cover and there will be a total of 13 images.
The release date is November 20th. To find this at other online stores, the item number is 9784049002928 and the price at Rakuten is 2000 yen.
(I don't think the image on the website is the actual cover image since Rakuten tends to use stock images to advertise their preorder items.)
Also, in case it was missed the CLAMP@MOBILE site is open. Much of it is members-only, but you can make a free avatar at this page.
Check out my summer-y Seishirou who has been shopping for pets. The sidebar has a links to the free clothing and other items. Experiment and click around the mobile site for other free access areas.