Delphi XE Development Essentials – by Bob Swart is a very good e-book covering new features in Delphi XE – as well as some new features in Delphi 2009 and even Delphi 2007.
Since most of my programming is done in Delphi 2007 and I plan to switch to XE2, I found the book quite useful.
I have been a little remiss on upgrading Delphi, mostly because since 2007 there was a complex process on the local reseller which even included sending them signed contracts in the mail. That was surprisingly worse than the very simple process from Delphi 4 to Delphi 2007 – simply accessing a site and either entering your credit card number or printing out and paying a boleto online. Thus I skipped 2 or 3 versions of Delphi.
Obviously the forced Unicode support in Delphi 2009 didn't help, as it will take a while to change applications to support it. XE2 is a bit exciting as it added 64-bit support. In most software 64-bit has no practical use at all, but I have several users that had memory problems with STG FolderPrint Plus after scanning several million files at once. This was much improved with supporting 3GB memory in 64-bit OSs a few versions back, though.
The book was quite useful, and cover a lot of ground, including Unicode support, new compiler options, new features such as attributes, generics, unit testing, code site, subversion and more.
Recommended to anyone switching from an older Delphi version, or even starting with XE. It is interesting to note that you can get it for free when you get the XE2 Development Essentials edition.