Javascript makes it a pain to get clipboard functionality working across all browsers. Flash is the lcd for this kind of thing. A cursory look tells me that it might be possible for firefox with signed javascript:
http://www.mozilla.org/projects/security/components/signed-s...
Exactly. There just isn't browser support for clipboard access right now.
However, it's not like clippy has any impact on CPU performance or usability (it's only added functionality, not blocking content for people w/o flash) so there's really no downside to it being in flash.
http://www.krikkit.net/howtos/13-howtos/16-copy-text-to-clip...
I don't think it will work on chrome though. IE probably.