I had to do some extensive testing before I got too excited, but after a conversation with the developers I'm pleased to announce that ExpanDrive 2.0 is out. We've mentioned it before, but to recap: ExpanDrive allows you to mount remote servers as drives directly accessible in Finder. With a completely rewritten (again) SFTP layer, the existing FTP support and new Amazon S3 (Simple Storage Solution) support, it's even more useful than the last time we mentioned it. One of the developers, Jeff Mancuso, mentioned to me back at the last WWDC that the S3 support was in the works; it's great to see it come to fruition.
In my testing, I found that a previously-existing S3 option, JungleDisk, can cause conflicts with ExpanDrive's S3 support. JungleDisk users should note that there are some issues, but they seem to clear up if you create vanilla buckets in your account and use those with ExpanDrive. I personally found that I was willing to give up JungleDisk entirely at this point, preferring this direct-mount with all of the perks, including a contextual menu in Finder for quickly setting public read/write permissions.
I can attest to the fact that it's faster, and that the S3 support is working (wonderfully, without JungleDisk). ExpanDrive 2.0 is a $39.95 purchase (well worth it if you deal with remote UNIX systems or S3), and a $19.95 upgrade for existing users. There's a free trial available.