Just picked one up last week
The 15-sheet thing is probably a typo, 150 seems closer to the mark.
Setup was easy. Removed lots of orange tape, switched on, followed the quickstart guide and had no trouble installing the consumables. Configured the WLAN manually from the top-panel controls and it worked first time. It doesn't obscure the WLAN key when entering it, which is a major plus in my book.
The duplex is slow, but if I'm ever in a hurry I can always switch it off. The last time I was in that much of a hurry for a printout to finish was after pulling an all-nighter writing a GCSE paper, even in duplex mode this thing hauls compared to the Amstrad DMP-2160 I was using back then. I can live with the duplex slowdown, in other words. :) If I really needed speedy printing I'd buy a laser printer anyway.
I have it wireless networked and the memory card slots appear as a Windows share named \\printername\canon_memory - the software tries to map a drive to it if you ask, but I had trouble with that part (something to do with the workgroup name, and the only problem I encountered). I just set the printer name to MP560, added \\MP560\canon_memory to my network places and was done with it. You do have to set this up in the configuration, it's disabled by default. Also it only works for memory cards inserted into the slots, doesn't work for devices connected to the USB port on the front. Can only see one card at a time.
Scanning to a PC on the network works nicely once you have it configured (MP Navigator is a bit fiddly to set up for the different scan types, and upgrading it to a newer version reset the preferences to default, AARGH!); choose the destination machine and the type of scan, then just scan each page of the document, or each photo with one button push. Scan to PDF will keep adding pages to the PDF file until you tell it you're done. About as painless as it gets with a one-sheet-at-a-time flatbed, really.
It can scan to a memory card or USB device (PDF or JPEG), but ironically cannot see those files when you go into the print from card/USB options because it doesn't use the DCIM directory standard when writing but requires it when reading (I can has firmware fix, plz?)
Supposedly there will be Linux drivers in "autumn 2009". How good they'll be is another matter. Since Lightroom won't run in Linux, it's a moot point for me. :-(
Overall impressed, though I'm waiting to see just how quickly it uses ink (the HP it replaced was a thirsty bugger).