For current Nexus devices may be - but for older gen Nexus devices I am not sure I have ever seen a same day update.
I'll just have to accept my fate, and pick up a Nexus 4 when I'm able.
That is absolutely not the brand I thought I was buying.
Edit: Sorry, that was a ruder tone than I intended. I've got a bit of a love/hate relationship with my Nexus S due to the OTA frustrations, but I do love that Android has the option for taking matters into my own hands.
After flashing yakju once, all the updates flow smoothly.