Rails Ruby on Rails

I use Ubuntu 9.10 from inside of Windows XP Pro.
I updated Ruby from 1.8.7 to 1.9.1 using RVM as explained at http://rvm.beginrescueend.com/install/.
Then I installed Ruby and Rails 3.0 as explained at http://weblog.rubyonrails.org/2010/2/5/rails-3-0-beta-release/comme.... I also installed mysql gem.
Here is the result:
@@@serge@ubuntu:~$ ruby -v ruby 1.9.1p378 (2010-01-10 revision 26273) [i686-linux]
serge@ubuntu:~$ rails -v
Rails 3.0.0.beta
serge@ubuntu:~$ gem list

LOCAL GEMS

abstract (1.0.0)
actionmailer (3.0.0.beta)
actionpack (3.0.0.beta)
activemodel (3.0.0.beta)
activerecord (3.0.0.beta)
activeresource (3.0.0.beta)
activesupport (3.0.0.beta)
arel (0.2.pre)
builder (2.1.2)
bundler (0.9.3)
cgi_multipart_eof_fix (2.5.0)
daemons (1.0.10)
erubis (2.6.5)
fastthread (1.0.7)
gem_plugin (0.2.3)
i18n (0.3.3)
mail (2.1.2)
memcache-client (1.7.8)
mime-types (1.16)
mysql (2.8.1)
rack (1.1.0)
rack-mount (0.4.6)
rack-test (0.5.3)
rails (3.0.0.beta)
railties (3.0.0.beta)
rake (0.8.7)
rubygems-update (1.3.5)
text-format (1.0.0)
text-hyphen (1.0.0)
thor (0.13.0)
tzinfo (0.3.16)
serge@ubuntu:~$

When I tried to install mongrel gem I got the below error:

serge@ubuntu:~$ gem install mongrel
Building native extensions. This could take a while...
ERROR: Error installing mongrel:

ERROR: Failed to build gem native extension.

/home/serge/.rvm/rubies/ruby-1.9.1-p378/bin/ruby extconf.rb checking for main() in -lc... yes
creating Makefile

make
gcc -I. -I/home/serge/.rvm/rubies/ruby-1.9.1-p378/include/ruby-1.9.1/i686-linux -I/home/serge/.rvm/rubies/ruby-1.9.1-p378/include/ruby-1.9.1/ruby/backward -I/home/serge/.rvm/rubies/ruby-1.9.1-p378/include/ruby-1.9.1 -I. -D_FILE_OFFSET_BITS=64 -fPIC -O2 -g -Wall -Wno-parentheses -o http11_parser.o -c http11_parser.c
gcc -I. -I/home/serge/.rvm/rubies/ruby-1.9.1-p378/include/ruby-1.9.1/i686-linux -I/home/serge/.rvm/rubies/ruby-1.9.1-p378/include/ruby-1.9.1/ruby/backward -I/home/serge/.rvm/rubies/ruby-1.9.1-p378/include/ruby-1.9.1 -I. -D_FILE_OFFSET_BITS=64 -fPIC -O2 -g -Wall -Wno-parentheses -o http11.o -c http11.c
http11.c: In function ‘http_field’:
http11.c:70: warning: format not a string literal and no format arguments
http11.c:71: warning: format not a string literal and no format arguments
http11.c:77: error: ‘struct RString’ has no member named ‘ptr’
http11.c:77: error: ‘struct RString’ has no member named ‘len’
http11.c:77: warning: left-hand operand of comma expression has no effect
http11.c: In function ‘request_uri’:
http11.c:102: warning: format not a string literal and no format arguments
http11.c: In function ‘fragment’:
http11.c:113: warning: format not a string literal and no format arguments
http11.c: In function ‘request_path’:
http11.c:124: warning: format not a string literal and no format arguments
http11.c: In function ‘query_string’:
http11.c:135: warning: format not a string literal and no format arguments
http11.c: In function ‘header_done’:
http11.c:172: error: ‘struct RString’ has no member named ‘ptr’
http11.c:172: error: ‘struct RString’ has no member named ‘ptr’
http11.c:172: error: ‘struct RString’ has no member named ‘ptr’
http11.c:174: error: ‘struct RString’ has no member named ‘ptr’
http11.c:176: error: ‘struct RString’ has no member named ‘ptr’
http11.c:177: error: ‘struct RString’ has no member named ‘len’
http11.c: In function ‘HttpParser_execute’:
http11.c:298: error: ‘struct RString’ has no member named ‘ptr’
http11.c:299: error: ‘struct RString’ has no member named ‘len’
http11.c:307: warning: format not a string literal and no format arguments
make: *** [http11.o] Error 1

Gem files will remain installed in /home/serge/.rvm/gems/ruby-1.9.1-p378/gems/mongrel-1.1.5 for inspection.
Results logged to /home/serge/.rvm/gems/ruby-1.9.1-p378/gems/mongrel-1.1.5/ext/http11/gem_make.out
serge@ubuntu:~$

Any idea how to install mongrel gem on Rails 3.0 beta and ruby 1.9.1 ?