Ho appena installato il programma senza problemi.
Ecco il log.

codice:
weppos:Desktop weppos$ git clone git://github.com/schof/spree.git spree 
Initialized empty Git repository in /Users/weppos/Desktop/spree/.git/
remote: Counting objects: 17803, done.
remote: Compressing objects: 100% (7503/7503), done.
remote: Total 17803 (delta 9453), reused 17593 (delta 9251)
Receiving objects: 100% (17803/17803), 6.45 MiB | 91 KiB/s, done.
Resolving deltas: 100% (9453/9453), done.

weppos:Desktop weppos$ cd spree/

weppos:spree weppos$ cp config/database.yml.example config/database.yml         

weppos:spree weppos$ rake gems
(in /Users/weppos/Desktop/spree)
 - [I] highline = 1.4.0
 - [ ] activemerchant = 1.4.1
 - [ ] tlsmail 
 - [F] active_presenter = 0.0.4
 - [ ] activerecord-tableless = 0.1.0
 - [ ] searchlogic = 1.6.3

I = Installed
F = Frozen
R = Framework (loaded before rails starts)

weppos:spree weppos$ sudo gem install activemerchant --version 1.4.1                
Successfully installed activemerchant-1.4.1

weppos:spree weppos$ sudo gem install tlsmail
Successfully installed tlsmail-0.0.1

weppos:spree weppos$ sudo gem install  activerecord-tableless --version 0.1.0
Successfully installed activerecord-tableless-0.1.0

weppos:spree weppos$ sudo gem install searchlogic --version 1.6.3
Successfully installed searchlogic-1.6.3

weppos:spree weppos$ rake db:bootstrap 
(in /Users/weppos/Desktop/spree)
This task will destroy any data in the database. Are you sure you want to 
continue? [yn]

Create the admin user (press enter for defaults).
Email [spree@example.com]: