Jon Udell has a nice and simple piece explaining the problems between delicious and delirious. From my own point of view I dont really care about the rip off-ness of the new service, end of the day there are many search engines and soical software apps which look simular but no one batters an eyelid. Honestly I would say its more of a compliment or a form of flattery. Anyhow the issue I do have is the open source-ness. I dont like my data not being mine, when I signed up to delicious I knew this but it was the only thing widely available at the time for bookmarking. Now I may change my bookmarks over to delirious because there is an alternative. I want my data to be under a creative commons licence which suits me and even though I dont have plans to build my own social bookmarking service, I'm more happy to know my data will not be locked into a service which could go bust. Yes you can get all your data out of delicious by using the API but thats not everything is it, I'm sure theres tons of linking information which I cant currently get my hands on. There's parellels between this debate and others like the attention.xml debate.
