If with "management" you mean designing and publishing InfoPath form
templates, the answer is "yes". You need at least 1 InfoPath client
application to be able to design and publish browser form templates.
If you mean filling out InfoPath forms, the answer is "no". If you've got
InfoPath Forms Services installed on SharePoint and want to fill out forms,
you only require a browser.
I came across this post and I'd just like to clarify:
If we have forms that are made available via InfoPath Forms Services
installed on MOSS, then users (internal or external) DONT NEED A MOSS CAL
license to access them and fill them in? I realise they dont need local
software, but on the license question - do they need one?