I doubt very much that it will be out in April. Everytime a new device is rumored people find references in obscure sites, if it was legit info youd see it on the homepage of CB.
I don't like rumours. Never-the-less, I will conversing with my friends working at RIM. It's always fun to shoot the **** with them about this kind of stuff.
6.1 was only recently pushed to update the Dakota which is still in the testing phase, I wouldn't look for it to available to the public for quite some time.