Normally perl will work fine using forward slashes instead of backslashes--even in Windows. So you can save yourself tons of headaches by using them:
my $dir = "//$server/d/logs/tomcat";
The only time I have problems with it is when I'm executing another program from perl. Then you may have problems with the shell handing special characters, the external program not wanting forward slashes, etc. But I rarely execute other programs from perl, so it hasn't been a problem for me.