I've certainly found myself I read a lot more short fiction on my Sony now, though in my case I tend to prefer anthologies - I buy a lot more of them than I ever used to in paper, and they work very well in the ebook context. Also, there's a lot of very good original anthologies around these days. John Joseph Adams is one of the most interesting anthologists around in sf and fantasy these days - I have his Seeds of Change anthology, and my eye on several others on sale at
www.webscription.net.
I did write on my blog a while back (it was later crossposted at the digitalist.net) that I wondered if short story collections as ebooks might be a very powerful promotional tool for novelists.