I haven't actually used it yet, but I just grabbed Poco and built the foundation. It comes with solutions for several compilers (including vc7.1-9.0) and a cmake project.
Poco is designed for modularity and the different subsystems are easy to isolate. Ignoring the xml (sax2 and dom) module, networking module, utilities module (command line and config file handling, and server apps) and unit testing module, the foundation module is the interesting one.
Foundation compiles to a single 6MB static lib (non static versions are an option too). It contains:
- platform abstraction (data types, big/little endian, os info, system debugger interface)
- memory management (smart pointer, shared pointer with reference counting garbage collection, singleton template)
- string utils (using std::string)
- error handling (exceptions and asserts with special debugger support)
- streams (stream based encoding and decoding of base64, hex and zip data)
- threading (threads, mutexes, events, locks, semaphores, thread pool management, scoped locks, timers, activities (background tasks), active methods (asynchronous tasks)
- datetime (microsecond timestamps and stopwatch, time zones, calendars)
- filesystem (cross platform file system stuff, directory iterator, temp file classes, file finding class)
- logging (console, file, unix syslog, windows event log, remote log, cascaded channels, filters, formatters)
- processes (synch between processes with global mutexes and events, shared memory, interprocess communication)
- shared libs (platform independent class to make plugin writing easier)
- notifications (type safe sending of notification objects both inter and intra thread, notification queue)
- events (synchronous and asynchronous events, similar to events in C#)
- crypt (md2, md4, md5, sha-1 message digests)
- text (converting between utf-8, utf-16, ascii, etc)
- regular expressions (perl compatible)
- uri (uniform resource identifiers)
- uuid (time, name and random based uuid generation)
- cache (generic caching framework)
They claim that Poco is designed to work well on small embedded environments, it's already being used on windows ce and qnx neutrino.
It might not provide as many random things as boost (octonian maths, graph path finding, complete c++ parser, etc), but it might be worth a look to see if it offers what ogre needs compared to boost (at the very least, there's no way their filesystem class can be as horrendous as the boost one, the only component of boost I dislike). Oh, and it's released under the Boost license.
(As I said at the top, I've never used it myself)