apt-listchanges is probably what you want.
On Mon, 2009-06-08 at 08:36 -0700, john wrote:
> Hi all,
>
> Is there an announce list for the updates to the "Main" repository or
> are packages just added there and end-users find out when they do
> apt-get update? For example I see that there's an update to "libsasl2"
> and "libsasl2-2". I can't find any information about the nature of the
> update. Perhaps if I knew how to ask apt it would tell me? Anyway I
> hate to apply patches that I don't have an idea about. So hopefully
> someone can enlighten me.
>
> Thanks!
>
>
> John
>
>