Little steps and all that. I know it comes as a shock to a lot of the internet generation but most business have a hell of a hard time changing their business model and surviving it, the bigger the company the harder it becomes as with everything in life.
This is a little step but it is down the right path. As much as we would all love to have the same abilities as we do with physical copies of books going the full wack of unlimited lending for unlimited timeframes is most likely too big of a shock for publishers to deal with. Hell we don't even have a legal way to do this with iTunes, Amazon MP3, and other online media services (at least not that I am aware of? please correct me if I am wrong, note I said legal, technically it is possible as there is no DRM but legally there is no way, it could be argued this is true for physical media too due to the "license" on the inside of the CD, DVD, or whatever it is you bought but no court would ever actually follow thru on that however sharing MP3s online doesn't get the same treatment, go figure).
Anyway back to my point, I am pretty sure in time limitations will be lifted, maybe not to the same as you get with physical media but pretty close. One thing that is the same, if you lend a friend a book you certainly can't keep reading! It would have been pretty cool (and a much bigger deal IMHO) if the publishers used this as a marketing tool for word of mouth advertising by letting you "lend" the book to a friend while you can still read it but limit the lending limit to 14 days (or N number of chapters, which is better in IMHO as people read at different speeds, only at the weekends, etc. Time limits are a pain in the ass whereas content limits make it a lot more user friendly, at least to me it does, it is also much easier to manage, no clever ways to check when it has been 14 days (dealing with users who never connect to wifi and just set the date back, etc), no hacks to have to patch in the next firmware update, etc. just lend the friend 50% of the book, not 100% but with a digital lock around it that will be broken before even 1% of the user base upgrades their firmware) That way they can probably exploit the "omg I just got this amazing book you should sooo buy it" factor when someone first gets a book but hasn't finished it yet so won't lend it to a friend, then they forget or it is crap and they just dump it in a book store and the publisher never gets to sell that friend a copy.
Just my 2c