I don't believe I've seen this discussed before and it's not a major issue for me but I'm pretty certain it may be for some people and I want to make you aware. Whenever you have a conversation on GTalk a copy of that conversation goes into your Gmail "All Mail" folder. Mine is full of GTalk conversations.
I like to store things in the archive which is the same folder, All Mail and this has really cluttered up my archive mail.
Any email you send out also has a copy of it stored in this same folder. If this is a concern for you you may want to go in and clean up that area. If anybody knows how to avoid Gtalk from being sent to this folder I'd appreciate you sharing it with me.