I'm just about ready to finish my decision on an iPad purchase, and I have one last (hah!) e-mail question that I haven't been able to determine yet. I use Thunderbird on my home PC connecting to multiple IMAP mail accounts (all with different send and receive servers). Also, I like the option that Thunderbird gives me of using whatever 'from' address I would like. Does the iPad e-mail program allow me a similar set of flexibility? I'm really looking for a single client that gives me a single address book spanning multiple e-mail accounts. A unified inbox is a nice plus, but not necessary. Is there someplace online that has the specs on the built-in apps that would answer questions like this? Also, does iBooks allow annotation of e-books? If not, is there an app for the iPad that does? Thanks a bunch!