i don't use auto posting, so i just tweet it with the tags. the tags include you in the search, forever, its not a small amount of time. how long the tags work in twitter is unknown, because they really only show you recent things. however google finds them and other bots as well. just like anywhere else, if you use a common tag you'll be buried. if you use special ones or unique ones, it will stay just fine.
you want tags because you won't be found otherwise. you have to depend on your friend base otherwise. with tags you create a funnel for other people to find you.
---Mike Savad
MikeSavad.com