I too felt a pang when I heard the Kindle would be available here at long last
But ultimately, think less about the brand and more about the features. For me, the two deal-breakers with the Kindle were that it does not handle library books and the prospect of converting all my books again; I have already done this once when I switched to the Sony from the iPod Touch. I know Calibre can handle all of my files, but I just can't be bothered. Kindle might be fun but the no library books thing is a deal-breaker for me, for now
So, looking at features the Kindle or Sony have but not the other:
Both have their own stores with free and paid books
Both have good quality e-ink screens
Both can read many formats with conversion sometimes needed
Both can easily be managed via USB
Both are great for reading general books and documents
Sony can handle PDF better (so I hear)
Sony can handle emerging standard ePub
Sony can use tags or collections to sort books
Sony can read library books from Overdrive
Kindle has dictionary lookup (but only for English)
Kindle has wireless
Kindle has note-taking abilities
Kindle can sync with an ipod
Kindle store has lowest prices (but sells in US dollars so you will have to convert every time)
I think either would be a solid bet, actually. But I do want to read library books still, and also I think Shortcovers will be coming out with a device within the next year, so I am going to sit tight for now and see what developments are on the horizon
I may upgrade one of these days, but with all the flux in the market right now and new stuff coming out, today will not be that day