portage 2.2 и сеты.

А разве такой сет существовал? О_о Вы хотите сделать это: emerge -p @system @world ?

И ещё, непонятна логика portage, выдающего такое:

# emerge -p @downgrade

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild     UD] app-editors/vim-core-7.2.182 [7.2.238]
[ebuild     UD] app-editors/gvim-7.2.182 [7.2.238] USE="-debug%" 
[ebuild     UD] app-editors/vim-7.2.182 [7.2.238] USE="-debug%"

app-editors/vim-core
     Available versions:  7.0.235 ~7.0.243 7.1.123 ~7.1.330 7.2.182 ~7.2.264-r1 {acl bash-completion livecd nls}
     Installed versions:  7.2.238(16:28:21 10.10.2009)(acl bash-completion nls -livecd)
     Homepage:            http://www.vim.org/
     Description:         vim and gvim shared files
…и т.д. в том же духе

# emerge -up @installed

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild     U ] sys-devel/gcc-4.3.4 [4.3.2-r3]
[ebuild     UD] app-editors/vim-core-7.2.182 [7.2.238]
[ebuild     U ] net-libs/xulrunner-1.9.1.2-r2 [1.9.0.14] USE="alsa%* python%* -debug%" 
[ebuild     U ] net-im/pidgin-2.6.3 [2.6.2]
[ebuild     U ] sys-libs/libcap-2.17 [2.16]
[ebuild     U ] media-libs/speex-1.2_rc1 [1.2_beta3_p2]
[ebuild     U ] www-client/mozilla-firefox-3.5.2-r3 [3.0.14] USE="alsa%*" LINGUAS="-as% -bn_BD% -es_CL% -es_MX% -fa% -hr% -kk% -ml% -or% -rm% -ta% -ta_LK% -vi%" 
[ebuild     UD] app-editors/gvim-7.2.182 [7.2.238] USE="-debug%" 
[ebuild     UD] app-editors/vim-7.2.182 [7.2.238] USE="-debug%"

и наконец, соль:

# emerge -up @installed-@downgrade

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild     U ] sys-devel/gcc-4.3.4 [4.3.2-r3]
[ebuild     UD] app-editors/vim-core-7.2.182 [7.2.238]
[ebuild     U ] net-libs/xulrunner-1.9.1.2-r2 [1.9.0.14] USE="alsa%* python%* -debug%" 
[ebuild     U ] net-im/pidgin-2.6.3 [2.6.2]
[ebuild     U ] sys-libs/libcap-2.17 [2.16]
[ebuild     U ] media-libs/speex-1.2_rc1 [1.2_beta3_p2]
[ebuild     U ] www-client/mozilla-firefox-3.5.2-r3 [3.0.14] USE="alsa%*" LINGUAS="-as% -bn_BD% -es_CL% -es_MX% -fa% -hr% -kk% -ml% -or% -rm% -ta% -ta_LK% -vi%" 
[ebuild     UD] app-editors/gvim-7.2.182 [7.2.238] USE="-debug%" 
[ebuild     UD] app-editors/vim-7.2.182 [7.2.238] USE="-debug%"

т.е. не обращается внимание на то, что я хочу обновить установленные пакеты, за исключением тех, которые перечислены в сете @downgrade, хотя, если я занесу gcc в отдельный сет и запущу предыдущую команду, дописав -@сет, то gcc в списке обновления не будет. Странно.