What is apollo?
runtime that allows devs to use (flash/flex/html/ajax) to build desktop RIAs
filesystem access
custom chrome
detect network (or lack thereof)

team need/pain
light-weight scrum tool for distributed and mobile (offline) teams
cross-platform

why not ajax?
offline
filesystem access
features (camera)
not in a browser

But, apollo plays with ajax if you want to

[maptacular demo]

combining apollo and rails
communicate from flash side using AMF serialization
REST

gotchas
Flex'isms
REST - use _method hacks for PUT DELETE HEAD; pass body on everything other than GET
Use POST with _method hacks
Use URLLoader to get HTTP Status Codes
Don't dasherize (ie don't use rails's to_xml), build your own xml using builder templates
Migrating to newer apollo builds (eg ApolloApplication vs Application)

http://labs.adobe.com/wiki/index.php/Apollo:Documentation