Short for Intellectual Public Property, #IPP is indicates that the content of your post, tweet, or blog is open content specifically intended for reuse and remixing with attribution, even if the rest of your ideas are not.
Other potential tags could be those relating to Creative Commons, such as #CCBY, #CCBYSA, or #CCBYNC, but I think #IPP is just a bit more catchy. Next time you tweet or blog, ask yourself, “Am I down with IPP?”