One key difference between sourceforget and the CPAN is that with the CPAN it is possible for you to take over maintenance of someone elses project if they disappear - that's how I became the Data::Compare maintainer. At sourceforge, you can't as far as I know, and if you want to take over you have to fork the software and create a new project.

In any case, if there are only 80,000 abandoned projects on sourceforge I reckon that's pretty good. Remember, almost all of the authors on sourceforge - just like on CPAN - don't get paid to write and maintain their stuff. It is a testament to the strength of the development model that despite that we manage to have several thousand perl modules and several tens of thousands of sourceforge projects which are either complete, under maintenance, or under development, and that many of those have hundreds if not thousands of users who rely on them to work reliably.

As an example of a successful project, for which the authors don't receive a penny in payment, take a look at rsnapshot (of which I am the current maintainer). It has a small number of core developers, several tens of people who have submitted patches, several hundred people on the mailing list, and those people use the software to back up well over a thousand machines between them, ranging from single desktop PCs at home through to the servers on a hospital ship, in casinos, and in government departments and other large companies.