Drupalcon in Philly would be pretty ambitious at this point, but not out of the question (referring to the Drupalcon proposal here: http://groups.drupal.org/node/12971 ).
As a complete air-drawing (cause it's not certain how possible it even is to host the 2009 Drupalcon here) What about discussing making the event more 'Philly-like' (place-sensitive if not city-specific)? Consider linking local orgs and non-commercial spaces, with small businesses (and a few large ones - universities are businesses too;) )... For instance, how about a city-wide event, with focused events in specific places on a schedule. There could even be more experimental meeting situations set up, following this model.
Philly of course can accommodate large conferences (the convention center for instance, expensive hotels, high-end restaurants)... but there are different sides to the city than that one... and there's a range of Drupal players other than the people those kinds of conventions attract - perhaps a Drupalcon in Philly could be modeled on other kinds of conventions, not modeled on those favored by the private sector.
One of the most intriguing aspects to me is the underground and self-organized element (non-commercial spaces, artist-run businesses even, informal groups, local bars, even more established non-profits) - why not emphasize some of this? Drupal is used for large businesses, fair enough - but it's also a tool used my many groups for self-organization and community-building. There may be ways these public and non-profit elements can work together with interested private initiatives in a city-wide conference like this.
Look forward to more discussion :)
Cheers!
Scott

Comments
Well...
I really doubt that DrupalCon is coming to Philly in 2009. If it was to come it would most likely co-locate with AIIM at the Convention Center. To be blunt, there is no possible way something like you've described could possibly accommodate a conference at this size (1500-2000 people), espescially when the biggest complaint at the last DrupalCon was that you had to walk a half-a-mile to get food (people want to stay in a single place for the conf).
It really has nothing to do with private vs. public sector, what you're suggesting is a logistical nightmare.
Alex Urevick-Ackelsberg
ZivTech: Illuminating Technology
Alex Urevick-Ackelsberg
ZivTech: Illuminating Technology
You may be right...
For Drupalcon, you may be right. I haven't been to one of those yet ;) However for other conventions - this is not a bad way to go - I've been to some rather large ones that made use of some of these options, and they were really amazing. It really depends on which area the grouping is located, where days are focused etc. But overall, I agree it sounds pretty unlikely Philadelphia will be the next site for Drupalcon anyway.
Best!
Scott