The patterns themselves should work on Firefox 3.6+, Chrome, Safari 5.1, Opera 11.10+ and IE10+. However, implementation limitations might cause some of them to not be displayed correctly even on those browsers (for example at the time of writing, Gecko is quite buggy with radial gradients).
If you have a new pattern to submit, please send a pull request. However, please bear in mind that I can't accept all submissions, sorry for that. For a pattern to be accepted, the following factors are considered (in descending order of importance):