Maybe we should talk about success of using Perl to build enterprise applications. Because, the BIG project is nothing. You can write more than 1 million rows of code and it wouldn't good example.

If we are talking about E-commerce the most famous example is eToys.com. Livejournal also can be a good example of BIG project based on Perl.

RT is an excellent example of short (it's totally about 200,000 lines) but well developed application.

I've developed for 4 years in the Billing System which based on Perl and Embperl (for user interface). We have more than 300,000 lines of code. It's not so much but our system's worked success about 3 years. It does all work: from receiving events (VoIP, VOD, Internet, Telephony, Web hosting etc) to issue invoices and processing payments. I cannot say that Perl is the best choice for this kind of applications. But I'm sure that it's much better then Java.

So, the number of lines in the code cannot be a good criteria of aptitude of some language IMHO. It'd be better to use the cost of development which may include number of developers, the time of development, the number of already made parts which can be used in the development, the cost of hardware needed to run application and so on.