You can select it all (if it's basically text) and then use the speak selection feature to have the phone read it to you (that feature can be enabled at Settings > General > Accessibility > Speak Selection).
Well, if it's a video or a podcast, then it should be a matter of just playing it back on the device. If it's a photo stream, then there's really not much that could be read (aside from perhaps some descriptions or ALT image information that might be present).
(Also RSS is more Really Simple Syndication or Rich Site Summary these days.)