Jasper's Keep Current Time userscript is essential for any Blogger user who saves a draft post to publish a few days or even hours later. Without it, your published post bears the date/time when you originally created the draft, not the date/time you finished it, which to me is a big pain in the proverbial.
Unfortunately, his original script doesn't work if you have a New Blogger (formerly known as Blogger Beta) blog.
But fortunately, Aditya has adapted Jasper's original userscript to come up with a script which does:
Keep current time userscript for New Blogger.
And he's very kindly tweaked it so that it works like Jasper's did, namely it keeps the "Keep current time" box automatically checked on draft posts, in case (like me!) you forget to check it in your draft just before you publish it - but it doesn't check that box where you're editing an already-published post, so it maintains its published date/time. Thanks Aditya!
I've not had the chance to check how well the date/time format follows your own blog's, but as far as I can see, generally it works great.
If you use New Blogger, unless you're that rare creature who can write and publish posts in one go you need a Keep Current Time script.
(For beginners: what's Greasemonkey and how to install GM userscripts.)