In Adobe’s Penguin.SWF blog, we can learn some details about the upcoming version 10 of the Adobe flash player for Linux:
They’ll rely on more libraries to be present in the system rather than provide them all by themselves in their own install. This apparently includes libcurl.
So if you get the RPM of the pre-release player, you’ll notice that it requires “libcurl.so.3” which is the old SONAME for libcurl (libcurl 7.15.5 was the last release which used the number 3) which no up-to-date distribution should provide anymore. Since october 2006 we’ve shipped libcurl.so.4.
Apparently, this made the Fedora people first implement a work-around for this that re-introduces the SONAME 3 from the same source the SONAME 4 is made from, only to a short while afterwards revert that decision…
An interesting side-note is how the Fedora people repeat over and over in those threads that libcurl with SONAME 3 and SONAME 4 use the same ABI, although that is not true (at least not by my definition of what an ABI is). The bump was not accidentally made.
Update: it seems some blame this 3 == 4 thing on Debian…