Often I post messages with many links to external resources that will probably go stale over time. A facility to generate a permalink to (say) archive.org or a mirroring facility might be helpful to secure resources over time.
Also, many firewalls block sites like flickr. I'm a contractor so I tend to be at the mercy of whatever network security policy happens to be in place at the site. Sometimes I would like to be able to post screen shots or other supporting files such as code snippets but I don't always have the option of doing this.
This situation is going to get worse over time as the blacklist vendors spot new sites. They also tend not to be overly concerned about false positives. 1337-ness is ephmeral - attempts to find more obscure sites are just an arms race against blacklist vendors.
You will find that none of the commercial blacklist vendors block (for example) slashdot.org as they know that they will get a serious PR backlash if they do. Given that Stackoverflow has quite a high profile these days an 'official' stackoverflow archival site would have similar political clout.
While it is (to some extent) reinventing the wheel I think that relying on third party sites to host such material is not always workable. A service 'material.stackoverflow.com' or similar for posting supporting material would help with such issues.