AlanTop talk about "How to update multi-working-copy one time." on his blog. I found that is not the most effective way.

To update1 multi-working-copy one time just:

• If we use TortoiseSVN, just multi-select the top folders of these working copies2 and the (right click) shell menu -> update (or other commands). That's it.
• Or, if you use command line, the most powerful effective way.

svn up d:/project01 e:/path/project02 f:/dir/dir2/project03

1. 1 For commands like commit will not work.
2. 2 Of course this needs the top folders of working copies are in the same folder due to the windows shell limitation.