Let me setup just one WordPress installation at siteA.com with 2 static pages along with a blog. I've two domains and I must arrange it to ensure that siteA.com shows the first page since it's webpage, and siteB.com would show page 2 because the home page. Both sites would share your blog contents.

Because the Wordpress installation resides at site A, how do i produce a seamless experience for that user who visits site B?

Say they key in http://siteB.com/. What must i do in order to show the first page only at that address? PHP include? Redirect? Wreck havoc on .htaccess?

Set them up on two servers and employ 1 database.

You can take advantage of Wordpress' Nourishes to exhibit your blog posts of site A on-site B.

However, from the Search engine optimization perspective getting exactly the same content on two sites is probably not advisable (duplicate content: http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=66359).

Is Wordpress MU what you are searching for? It is within the full release and are available here http://codex.wordpress.org/Create_A_Network

Tricky, but most likely possible, though I am unsure why you would get it done by doing this, to tell the truth. You will need to modify each WordPress install to make use of some different tables for various things, i.e. site info (base URL, etc.). Observe that at runtime you may also make use of the HTTP_HOST header to find out which "site" you are exhibiting things for, however i suspect noodling using the tables will enable you to get the majority of what you would like.

See http://wordpress.org/support/topic/share-certain-parts-of-a-wp-database-over-2-domains for more info.