This is just a post to direct people to the CI Feature Matrix that ThoughtWorks maintains. If you're up in the air about choosing a CI system, then this is the page for you. They maintain an unbiased view (their words, not mine) of all the CI systems out there (and there are a lot of them). So if you're wondering or looking for something, check it out.
Note: TW says the page is unbiased and I believe them, however when anyone puts together a matrix like this sometimes they tend to include features that only *your* system has (so you can create a checkmark in that column) that no other system can measure up to. I don't feel TW did this here, but I do want to point out this for making your own unbiased comparison.
If anything, the matrix can be used as an idea generator. Wherever you see a red 
and the project is open source, maybe it's time to sit down and write a plugin/patch/add-on and contribute! Think about it and give it some consideration, it would only make these projects even better with more capabilities.