I would just use SimplePie and set it to get the most recent post from your FlatPress blog's RSS feed.
Here's an example which displays the last post from the official FlatPress blog.
SimplePie-Example.zip (71kb)
Just change the feed url on line 13 to show your own blog's feed address. It should be pretty easy for you to work this into your own web page, or build one around this example.
If you look at line 74 it shows you how to set it to display however many posts you want, but this example is set to just display the last one.
No, sorry - I've never been that deep into it. I just use v1.2.1 which seems to do what I need - that's the version which is in the zip file I linked to.
I changed the feed url on my example page to your own feed. Maybe you could check it now then do a test post to see if it changes when you refresh the page. I just tried this with another FP blog I have and it worked ok for me.
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