Can I see the currently checked out revision number in Tortoise SVN?

Right-click on the working directory in windows explorer, and select "Properties" (Not TortoiseSVN->Properties). You will see the Properties dialog, which will have a tab called "Subversion". Click on it, and you will see the version number, and other info.

Not in tortoise but in command line.

svn info

will return what rev you are checked out on.

TortoiseSVN -> Show log: The line in bold marks the current revision in your working copy.

If you are using XP, change your Explorer windows to Details View. Navigate to an SVN-controlled folder then go to View > Choose Details and select the SVN columns for status/rev/etc.