Signup system with Twitter-bootstrap

[thoratl]

Is there any standard sign-up system that I can use with Twitter-bootstrap?
Im thinking og making a application with the Twitter bootstrap but I need 
to be able to have users signing in to the user section.
 
Is it complicated to do that or is there plugins/Extension avaliable in 
Twitter bootstrap to do that?
 
I have never used Twitter bootsrap but it looks very good.
 
Hope someone can answer me.
 
Cheers
Thor