London - Olympic Park
In terms of things that already exist, no. Olympic Park has been constructed primarily on disused land. The buildings and stadiums erected are new, with little to no surrounding existing infrastructure. Depending on what venue you will be at, you may be relatively close to Stratford Westfield, a newish mall with food options ranging from food-court to restaurants. On the other side of the park you'll be closer to Hackney, but without knowing yet how long it will take to get back through security, it may not be worth the travel if you need to go back into a venue.
I took a bus tour of the park earlier in the week and the current food options are burger trucks for the construction workers and the shell of what's to be the biggest operating McDonald's in either Europe or the World. The 2012 games has a food charter, giving strict rules about sustainability and local sourcing, however I believe that sponsors get an exemption.
If you're asking more about places to go in the area because you're staying there, rather than just visiting events, people on the UK board will be able to recommend good food in the east and south east that will be more suitable for any free time that you have around any events that you have tickets for.
There are actually quite a few places nearby/very close (not on the park), and some really nice cafes within a walk (and of course there is Westfield which has an array of places. The View Tube is a great cafe with a brilliant view across the park and there are some nice pubs.
Check out this website for some more options, all within walking distance http://www.eastvillagelondon.co.uk/on...