When you publish an InfoPath form to MOSS 2007 (or forms server) through administrative mode, you can point to the form via a URL so that users can fill out the form from virtually anywhere. You can also do things like set a redirect page so that when the user is done filling out the form, the browser redirects the user to a workflow initiation screen or some other useful location.
Here are the query string parameters that control behavior in InfoPath Web Forms:
XsnLocation - What form to open and from where
XmlLocation - What initial data to use
OpenIn - Open in browser / client / either
SaveLocation - Save Location for data
Source - Navigate URL when form is closed
Example: http://MOSS2007/_layouts/formserver.aspx?xsnlocation=/formservertemplates/loanapplication.xsn&openin=browser&source=http://redirectpage