A Public Service Announcement:
it's = it is
its = ownership.
This is probably the most common mistake writers of English (be it student papers, blogs or what have you) make in their everyday prose.
Now, for those of us who are simply chattering away and get it wrong, all right. We should (and do) know better, but OK. However I expect better things from publishing. In rereading Dorothy and the Wizard in Oz last night, I observed that it's was always used to show ownership, even though it is wrong, wrong, wrong. L.Frank Baum didn't do this - it's some (insert swear word) editor who figured that this author person has been dead for 90 years and didn't know what he was doing at the time.
"It's a lovely day." = It is a lovely day.
"The Colts are getting a new stadium and it's terrific." = The Colts are getting a new stadium and it is terrific (meanwhile I use the pile of dirt as a navigational landmark.)
"I have a new calendar. Its pictures are all funny." = I have a new calendar. The pictures which belong to it (ITS, people, no apostrophe!) are reasonably amusing.