I'm trying to map a picklist field on Lead to a matching picklist field on Opportunity when doing the conversion. This field doesn't seem to be available when going to 'Map Lead fields'. Could this be because the Opportunity field has a field dependency and so would stop the conversion/insert of the opp?
I found the answer to my question in a knowledgebase article.
The gist of it: Standard Lead Fields cannot map to Custom Opportunity/Contact/Account fields.