Use user-agent or javascript to do this. Seems like a good idea. I'd much rather see "HN | Startup Title Ju..." than "Hacker News | Startu..." in my tab. Especially if I'm trying to remember which HN tab I'm trying to get back to.
(edit: actually "HN | Startup Title Junk" all fits in the tab with my font config)
(edit: actually "HN | Startup Title Junk" all fits in the tab with my font config)