List new packages after an apt-get update

[Graham Williams <Graham.Williams@cmis.csiro.au>]

After doing an apt-get update there are two types of packages I'm
particularly interested in: newly available packages (new to Debain
since the last time I did an apt-get update) and packages I have
already installed but that have been updated since the last time I did
an apt-get update. (I.e., ignore packages that have been updated but
not since the previous time I did an apt-get update)

Are there any simple command line methods for getting these two lists
(or do I need to persist in learning what seems to me to be the quite
un-intuitive interfaces in deity and aptitude).

Many thanks in advance,
Graham