I purchased a Nokia E61 to replace my Treo 650 from a US importer last year and have since upgraded to a Nokia E61i, again via a US importer. Nokia posted a press release announcing that Nokia E-series, these are the enterprise focused devices like the E61i, are broadly available in the United States. The release is primarily an educational announcement to spread the word about various outlets where you can get a Nokia E61i, E65, or other Eseries model. There are more than 140 value-added resellers (VARs) in the Nokia for Business Channel Program, including Dell.com, Gateway, and Mobile Planet. I personally have purchased my Eseries devices from PhoneSource USA and have been extremely pleased with their services. IMHO, the E61i is a great deal at around US$400 for a SIM unlocked device that requires no contract extension or minimal service obligation.
The Eseries devices are S60 smartphones with pre-installed applications and features focused on the business user. Devices like the E61i and E90 have QWERTY keyboards and just about every wireless radio you can think of to allow for VoIP telephony and connectivity anywhere. There are several syncing and push email solutions as well as the ability to view email attachments. The Nokia Intellisync Mobile Suite also allows for high security managment of the devices, which is critical to the business user. All of this isn't to say that these devices still can't be used for fun and personal enjoyment since they have MP3 capability, some have cameras for quick snapshots, and they support a large number of 3rd party applications.
Thanks to my buddy Chris over at Mobility Site for the link to the press release.