As with genes, the key role of memes, from the meme's eye view, is to replicate.
With the blogosphere, RSS aggregators/readers and Web 2.0 tools like del.icio.us, technorati and flickr, memes are replicating faster than ever and being sent to thousands of individuals upon each post. However, replicating and sending does not ensure reading. RSS readers, technorati and del.icio.us actively draw information to individuals based on subscriptions and key words requests, but with information overload, it is possible that many posts are never read and that many memes are never spread.
A meme is not spreading successfully unless it is read, by a being with cognizance, currently human, and passed on, possibly with variation and expansion. Memeticists might argue that per Darwinian evolution, the best memes are able to compete successfully for human attention and the ones that go unnoticed and deleted in RSS readers, etc. are not the fittest. Also that the proliferation and replication of many memes is better than less proliferation since there is a greater chance for fit memes to survive and thrive. This assumes the quality filtering the human must do is not detrimental to his/her absorption of fit memes.
Memes are still quite dependent on their symbiosis with the human substrate.