I'm also glad to see some progress on this topic. If I may add my 2 cents though, doing it 
the simple way first, by using svn if available in the path, would already cover 90% of the 
situations and bring the most value at the lowest implementation effort.

The point 4) from msg320 and the extra features 1) & 2) could always come later.

The fact is that Subversion 1.6.x is out since ... a year or so? and issue64 is still 
opened, which is a situation that could have been avoided if the simple approach suggested 
here would have been taken earlier.

Let's also have in mind that Subversion 1.7 will have wc-ng and therefore ''no'' private 
files to mess with, making point 1) from msg320 moot. Unless of course you want to look into 
their sqlite database file with the Pysqlite2 bindings... which would be another bad idea.