What you need to do is to show him that by attending the conference, which costs him your time (other things you could be doing) as well as money (other things he could be buying), that it will save him (your development) time or money over the next year or so. Socializing with a bunch of cool guys isn't going to cut it. The hard question he's asking is what are you going to find out/learn that you won't in the normal course of you doing your job over the next year or so. (and how much is it worth to know that now instead of later?)

The answer is going to be highly dependent how your company is using Perl and his opinion of where you are in your professional development (not just as a savy Perl guy). It's very difficult to find specific items 'cause he can always ask "couldn't you learn that from a book?" Unfortunately, for you in your situation, the main value of these things is in the socialization. Smart people exchanging viewpoints and experiences about something in which they have a common interest.

In my experience, the best way to get to attend an event like this is to do a presentation. One, this puts you on the schedule, barring disaster you'll be there. Two, guaranteed you'll get to know the organizers at least and probably some of the other presenters. Three, you'll learn more about your chosen topic than you otherwise would have. Four, conference attendees will want to talk to you as one who knows.

So, how do you do that? Start by attending your local Perl, Linux or Apache users group. Find something that you or your company has done that you think will interest them. Failing that, find something that you've done that interests you. Put a presentation together and give it at one or more of the meetings. Repeat as necessary until you're comfortable with it and believe you have a solid presentation. Then approach your boss (who should be aware of your activity) and let him know that you'd like to do the presentation at the conference. At this point, you've demonstrated that you're part of the community and not just a spectator. You have something of interest to say and the company gets to bask in the glory as a place where cool people do cool things. The conference is now part of your professional development, not just a social event or perk 'cause there's extra money in the budget.

Have fun,
Carl Forde