I was going to post this as a question, but found the answer while composing the message, so I'll just post the end result here.
SQL2000 and Reporting Services unattended installs allow for a space after the file paramenter. Analysis
Services doesn't seem to.
Thus, this will not work (for Analysis Services):
start /wait [path]\setup.exe -s -m -sms -f1 "[path]\msolap.iss"
But this will:
start /wait [path]\setup.exe -s -m -sms -f1"[path]\msolap.iss"
Sheesh! I won't tell you how long it took me to figure this one out.