C: 113
=

<!-- language: lang-c -->

    n,c,l;main(i){for(scanf("%d",&n),l=2;n;l=c==i?n-=i==l+2,i:l,i+=2)for(c=2;c<i&&i%c++;);printf("%d, %d\n",l-2,l);}

Sample run:

    $ for i in $(seq 1 10); do echo $i | ./twinprimes; done
    3, 5
    5, 7
    11, 13
    17, 19
    29, 31
    41, 43
    59, 61
    71, 73
    101, 103
    107, 109

Thanks for help from Dennis, bebe, and Alchymist.