I dont know anything about sponsoring (semi)academic conferences, and here is the fruit of my knowledge.
Where the survival of an event depends on its sponsors, then it had better overdeliver to today’s sponsors to ensure there will be some tomorrow. It also helps to be clear about why someone might be interested in becoming (continuing to be) a sponsor. Selling to the people physically at the conference is going to be fairly low down on the list. Making the decision-makers feel good about supporting the lisp community is a perfectly valid reason. So is making employees (current and future) feel good about their employer. This can go further – if competition for talent is tight (think Hyderabad – or the Bay Area – or any top school) a company could distinguish itself as being OK with quirky but seriously powerful stuff by associating itself with Lisp. And if there are other market segments which still have good vibes about Lisp (and let’s face it, a lot of folks think smug lisp weenies have something to be smug about) any organisation interested in those customers would gain from a sponsorship.
As long as the right folks know about the sponsorship. Appearing on the back of the conference program isn’t going to be enough. Of course, much of this is up to the sponsor themselves – they should ‘activate’ the sponsorship by integrating it into their own sales and marketing programs (hence all the ‘a proud sponsor of…’ stuff tacked onto ads). The event can help here by having a nifty logo early enough before the event itself to allow some sort of consumer recognition to develop. The event can also help the sponsors to reach out to (the vast majority of) folks who can’t/won’t attend. A sponsor-recognition strip below the projection screen (and/or on the lectern or the debate table) means all those seeing the talks on youtube (or looking to see what someone they know from irc looks like irl on flikr) will be able to see who supported the event. The AV coverage could even be separately sponsored (“ilc11cast brought to you by NTTDoCoMo, your first choice for a fulfilling engineering career”). And encouraging/providing facilities for podcasts (rooms to interview the celebs etc) would also enable the event to reach out and touch more people than are physically present. (Even something as simple as allowing a sponsor to provide branded lanyards for the badges means that sponsor will appear in every photo and video of the event and its surrounds.)
None of this should be taken as a criticism of ilc09 – I can only imagine the sponsors are very happy to have been associated with such a success. But why keep my ignorance to myself?