If you’re using RCP or even Eclipse itself, you’re using SWT. So… who’s using SWT? Lots of folks are. Ian Skerrett gave some examples of folks using RCP (and SWT by extension) in an blog entry several months back.
If you’re using RCP/Eclipse, you’ve also been using Eclipse’s OSGi implementation. You can find out more about what Eclipse is doing with OSGi by visiting the Equinox project page.
[Updated Sept. 20/05 to fix misspelling of Ian’s last name. Yikes and apologies…]