Pipelining allows Opera to make multiple requests without waiting for an answer. Basically it is the difference between calling someone multiple times asking for different items versus calling once with a list. Chunking is the splitting up of documents. Once chunked the document can be sent over a persistent connection through a pipeline. Each chunk is a known length so by splitting up the document in chunks even documents that have no known length can be sent.
Opera is served more details.
These details expand the caching capabilities because they allow more information to be held. Information like how old a document is, how long before it should be refreshed, or if it should be checked every time. Under the Hood HTTP 1.1 has furthered the speed of Opera. Opera is serving you documents faster, and with HTTP 1.1 increasing the general efficiency of the Web. It is relieving congestion and utilizing better methods of caching.