We've already been hearing a bit of chatter about a possible Mac Pro refresh coming to WWDC next week. Inventory has been dwindling at various retail locations, and that usually means new models are incoming. Furthermore, it's said that an Apple project manager responsible for the Mac Pro mentioned that an updated model is coming later this year, and it'll supposedly blow your mind.
RedUser.net forum member Drew Baird said he spoke with Mac Pro project manager Douglas Brooks about the tower computer after Baird initially mentioned some of his concerns about the Mac Pro. Brooks assures Baird that Apple is "doing something really different" with the Mac Pro. Whether or not this means just faster components or a completely new take on the Mac Pro line is yet to be known.
Again, no details were disclosed, but from the tone of Brooks' words, it sounds like the Mac Pro will be getting a complete overhaul. It's likely that Thunderbolt will be a big focus, and FireWire may be out the door for the towered machine. We could also be seeing newer and faster components, including new Intel Haswell chips, most likely.
The last time the Mac Pro was updated was last year during WWDC 2012, but we wouldn't count that as a significant upgrade by any means. Apple didn't mention the Mac Pro at all during their keynote, and they only quietly updated them in the Apple Store without much fanfare. However, it seems like they'll be giving the Mac Pro a lot of attention this year, since the last major update to the machines was well over a couple of years ago.