You see, I know this might shock everyone, but the IRC chat is a place where people, including many of the developers of the game, hang out and talk about random shit. This means that sometimes, people who are developing the game talk about things they're actively doing while they're doing it, such as joking around about a bug they just fixed or posting amusing WIP stuff. Most of this stuff is the type of thing that isn't nearly polished enough to show on the front page or the forums because those have a more permanent record of what's displayed. In a chat room it's okay to post obviously unfinished stuff because it's a casual conversation and while it's entirely possible to save logs, it's not like we actively archive everything that goes on a web page for search engines to index for posterity.
If a casual conversation about random bullshit that may occasionally include SRB2 sounds interesting to you, then by all means, join IRC. You might get occasional tidbits about development from the dev team as they happen. However, if you just want those tidbits, you're way better off just waiting until we get far enough along on these various things to post the more polished stuff on the front page.