I had the same decision to make when it came to my next DSLR. I went for the 50D over the 60D for these reasons.
50D Pros:
Faster burst
Larger + more comfortable
CF cards (more reliable in my experience than flimsy SD, plus I already have 8GBs worth)
Magnesium body (rather than Alluminium)
60D Cons:
Video mode (Dont want to pay for what Im not going to use)
Bendy Screen (Can be useful BUT flimsy and my Grampa has a Lumix G1, a piece of sand got between the LCD and the body and made a mess of the LCD :S)
Lock on Mode Dial (I have never nudged a mode dial by accident)
Of course the 60D does have advantages such as higher resolution and likely better noise control.
They key I believe for a second is ease of use. Do you really want to have to learn all those new controls? The 50D > 60D seems to be canons biggest revision when it comes to control lay out. I've had a play and it was just too weird for me,too different from the 300D and 350D I had previously.
Also, you will already know how you like your 50D set up from experience, its a case of re learning that too. And you can use the compact flash cards you already have.
I reckon you should go for another 50D, its an ace camera and unless you intend to use the video mode, the 60D just isn't necessary.