Wow, thanks for responding so quickly.
We have some third party modules installed (found here) that re-write URLs for sure, but I'm not sure if they are using iFinity URL Master or if it's some custom re-writer.
I looked around in the the admin section(s) that control their modules, but I couldn't find any options for changing the way spaces are replaced in URLs.
I've also looked at the web.config and found the following:
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<friendlyUrl defaultProvider="PFFriendlyUrl">
<providers>
<clear />
<add name="PFFriendlyUrl" type="PackFlash.DNN.Modules.SEO.PFFriendlyUrlProvider" includePageName="true" regexMatch="[^a-zA-Z0-9 _-]" urlFormat="humanfriendly" />
</providers>
</friendlyUrl>
-------------------------------------------------------------------------------
I'm going to play with the regex defined here and see if I get any results.