There must be a bit of misstep somewhere in your process, I created a sample app, using the following commands - hopefully this will help you identify where things aren't going right.
Just the list of commands:
$ rails new sample_app
$ cd sample_app/
$ git init
$ git add .
$ git commit -m "Initial commit"
$ heroku create
$ git push heroku master
$ heroku open
And the commands, with some truncated output:
$ rails new sample_app
create
create README
create Rakefile
create config.ru
create .gitignore
# ..snip..
$ cd sample_app/
$ git init
Initialized empty Git repository in /sample_app/.git/
$ git add .
$ git commit -m "Initial commit"
[master (root-commit) 487a313] Initial commit
37 files changed, 1138 insertions(+), 0 deletions(-)
create mode 100644 .gitignore
create mode 100644 Gemfile
create mode 100644 Gemfile.lock
create mode 100644 README
# ..snip..
$ heroku create
$ git push heroku master
Counting objects: 63, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (47/47), done.
Writing objects: 100% (63/63), 24.81 KiB, done.
Total 63 (delta 2), reused 0 (delta 0)
-----> Heroku receiving push
-----> Ruby/Rails app detected
-----> Detected Rails is not set to serve static_assets
Installing rails3_serve_static_assets... done
-----> Configure Rails 3 to disable x-sendfile
Installing rails3_disable_x_sendfile... done
-----> Configure Rails to log to stdout
Installing rails_log_stdout... done
-----> Gemfile detected, running Bundler version 1.0.7
Unresolved dependencies detected; Installing...
Using --without development:test
Fetching source index for http://rubygems.org/
Installing rake (0.9.2)
Installing multi_json (1.0.3)
Installing activesupport (3.1.0.rc6)
# ..snip..
-----> Compiled slug size is 5.6MB
-----> Launching... done, v4
http://gentle-water-874.heroku.com deployed to Heroku
To [email protected]:gentle-water-874.git
* [new branch] master -> master
$ heroku open