that's not correct.
the mormon church does NOT teach that being gay is a sin, therefore there are many gay people who enjoy all of the rights and blessings of full membership.
and while the church DOES forbid engaging in homosexual behavior, transgressors are NOT summarily excommunicated as you suggest.
church discipline naturally varies a bit from bishop to bishop, but from accounts i've heard and read, homosexual fornication is treated similarly to fornication in general. the discipline can vary from just the loss of temple rights (obligatory) to disfellowship to excommunication. it seems to depend largely on the person's willingness seek forgiveness and try to avoid future transgression.
you ought to learn more about your church before you go speading the "good news."
Man are you wrong. see Church's attitude toward homosexuality Openly gay members are excommunicated as long as they or practice it or teach that it is OK to practice it. If a Bishop does not excommuniate them he is not following church doctrine. Please inform your Regional Representive after taking to your Bishop and Stake President if they are not responsive. They will be disciplined and replaced if necessary. This happend to an entire Stake in Utah for teaching that children couldn't attend church.
Now expirementors and other members that came to their Bishop with the intention of repenting are not exfcommunicated automatically. I indicated as much saying we "try to love them into changing their ways."
You are right people seeking repentance are given that chance although all bishops should take Temple rights away in this case for a period of time.