I'd mentioned this idea earlier in the Fall on my Facebook feed, and I believe my agent brought this up at an LMDA conference as well, to largely positive response.
Each year in November/December I apply to about 11 summer development conferences and they all ask for the same thing: my play (sometimes anonymous, sometimes not), my resume (or sometimes a bio), a synopsis of the play and a casting breakdown, and a one-page application statement.
I send the same exact play to all of these conferences, and say pretty much the same exact thing in my statement (sometimes tailoring it a bit here or there). Yet I spend about an hour on each application, mostly sorting through each conference's particular set of submission requirements.
These conferences get about 600 submissions a year. (I know that because during Spring Rejection Season invariably I'll get 11 rejection letters informing me that my play was carefully considered among 600 talented applicants... *WAAAAAAH*... but I digress...)
If the summer development conferences were to create a common application online - like they do for colleges - you'd be saving 600 playwrights 10 hours of their time every year. That's 6,000 hours a year. (I know it's dangerous to just brazenly multiply a projection, but I do it for rhetorical purposes knowing that the principle itself remains solid.)
On the writers' side, a common app would save us a boatload of time and in those rare instances where a writer is unaware of a conference (or doesn't have it together enough to juggle all those deadlines), our work would be reaching a wider body of decision-makers.
On the conferences' side, sharing resources might cut costs, allow for increased coordination and exchange of ideas between conferences, and might attract new grant support (since - especially for the smaller conferences - it may be easier to garner new funding collectively). For instance, creating an online common app seems perfect for a TCG/MetLife ThinkIt/DoIt grant. Garnering funding as a group might also reduce reliance on onerous annual application fees levied on playwrights.
Over the long term, thinking of these development conferences as a collective rather than as a gaggle of individual groups might also yield interesting collaborative possibilities. For instance, doing a shared press release of the work that's been chosen might make play selection more of an event and attract future production support for the plays. (I'm thinking particularly of the upfronts in television, which is when all the TV networks announce their entire fall lineup, all at pretty much the same time.) Or in the case of plays of particular promise and scope, it might be interesting to send a play through multiple conferences in a coordinated way. (This already happens for a few lucky writers, but it's by chance and not by design.)
One argument against doing all this is the concern that all the conferences might end up picking the exact same plays. But I would argue that these conferences are already getting the same plays from the same pool of applicants, just in a way that's inefficient for both parties. With a common application, each conference's unique aesthetics would still guide their decision-making, which should yield the same kind of aesthetic diversity that's happening now.
The point is that there's no real "TCG" or "LORT" for development conferences (since these things are relatively new), but now that summer development's here to stay you might as well form an alliance, starting with something that will make writers' lives much easier year in and year out.