Most of the SVN commands and most of the SVN C/C++/Ruby/Perl/Python interface routines finish with a revision number. I realize there's Subversion Info but it'd be really nice if, upon completion, you could assign the revision number returned by an operation into a variable. (I've not found my feet enough yet to try and do this myself in action studio :)
I agree it is something we should add, I will look into it. In the mean time you can use an Output Monitor on the actions to extract the value into a variable. Open the action properties dialog, switch to the Runtime tab, click on the … button for Output Monitors, then click on “Add New Output Monitor”,
Search string : Checked out revision (\d*). Check Regular Expression Behaviour : Save first match to variable Variable : set it to your revision variable.
You will need to update the search string to match the action, I tested this on the checkout action but it should work the in the same manner.