I'm designing a lifestream plugin that imports from RSS feeds and stores the data locally. I don't want to use simple magpie caching because I eventually want to make the imported lifestream data show up in tag searches (i.e. posts tagged 'london' will show up along with my flickr photos tagged 'london' and my delicious bookmarks etc).
I'm thinking rather than creating a new table, I could store this info in the wp_posts table using a different value for the post_type column, e.g. 'lifestream'. Presumably such 'posts' would be completely ignored by the wordpress core leaving the plugin free to do whatever it wants.
Can anyone see a problem with this and if so suggest a better solution?