Andro ID - I believe using a 3rd party app such as Light Flow and selecting "white" as the color will create a nearly always on blink rate. I believe Handcent SMS and the customizable notifications will support this as well.
I would love the rate to be quicker, but would prefer not to mess around with Light Flow or other 3rd party app for notifications. When I did with my Photon, I stopped getting the appropriate email notifications.
Hopefully this gets addressed in a future MR or the hopeful upgrade to ICS.