The easiest way of doing this is to use a slightly undocumented feature of twitter's search - you can pull an Atom feed for any search query (which includes hashtags), and then use FeedWordPress to generate posts.
A sample Twitter search query that returns Atom (which is is an alternative to RSS and works in the same way):
Use FeedWordPress to create posts in whatever category you want from the twitter hashtag feed.
To set a category do the following: (from the FeedWordPress FAQ):
- Log in to your WordPress Dashboard using your administrator username and password.
- Go to the FeedWordPress administrative interface by clicking through to the Syndication page.
- Pull up the Categories & Tags settings page for the feed whose posts you want to apply the category or tags to. The easiest way to do this is to go to the "Syndicated sources" table and hover your mouse over the source that you want to work with. Several options should appear underneath; click on "Settings > Categories & Tags."
- To add one or more categories to any posts that come in from this feed, scroll down to the Categories box on the Categories & Tags Settings page, There should be a selection box marked "All posts: Give all posts from this feed these categories." You can check whatever category or categories you want. To add one or more tags to any posts that come in from this feed, scroll down past the Categories box to the Tags box; there should be a text box marked "Tag all posts from this feed as..." Type in one or more tags, separated by commas, and mash the "Add" button to apply them.
- When you've finished adding Categories and Tags, mash the "Save Changes" button at the bottom of the page.