Among the big news from the WWDC 2011 keynote was Apple unveiling iMessage for iOS. iMessage allows users of any iOS 5 device, whether its an iPad, iPod Touch, or iPhone, to send text messages, photos, video, locations, and more, without having to pay for text messages.

Carriers are probably pissed about this, as Apple apparently did not tell them about the new feature prior to the keynote, and it runs the risk of cutting into carriers’ bottom lines. And who else is pissed? RIM, of course, since iMessage spits directly in the face of BlackBerry Messenger.

Our source reports that iMessage works both over Wi-Fi and 3G, includes new features such as read receipts, the ability to see when someone is typin back/responding to you, and secure encryption of all the messages you translate. What’s more, you can begin messaging on one device, and pick up right where you left off on any other iDevice linked to your AppleID.

Although iMessage only works on iOS 5 devices, and has no support for other platforms, the fact that iOS has such ridiculous market share means that this probably won’t be that significant of an issue. I also imaging that Apple might, at some point, choose to merge this service with iChat to bring support for instant messaging. Additionally, you can register additional email addresses with iMessages beyond your Apple ID and even change your iMessage ID from your phone number to an email address. You can also disable iMessages or SMS messages in Settings, if you’re traveling abroad and worried about data usage.

One worry that I have is the lack of support for the Mac – I would think it very interesting if iMessage became a feature of iChat, so I could ping all of my buddies on the iPads or iPhones, regardless of whether they were signed in to instant messaging services.

Our source reports that investors in RIM were pretty hard on the company after Apple unveiled iMessage – reports indicate the the stock slipped as much as a full 3 percent. iMessage directly challenges RIM;s BlackBerry Messenger (BBM) chat service, offering much the same functionality, but with much greater device share, thus making it significantly more useful to the end user.

BlackBerry Messenger, once the lone wolf in the world of instant messaging services, now has a bigger, stronger, more capable competitor to play it out with – and that’s something they should rightly be nervous about.

[All Images Courtesy Of Publicly Available Apple Press, Marketing, or Advertising Materials]