If you are talking about the SWITCH program, that is an offer to give a discount to people with other software... only you know if you need what is in that bundle
As far as CS6, no employee (who wants to stay employed) is going to say exactly WHAT will be in CS6, or WHEN it will be issued
Adobe CEO on CS6 plan http://prodesigntools.com/when-adobe-cs6-coming-out-creative-suite-6.html
Whether or not to buy RIGHT NOW depends on a couple of things:
1. Do you NEED the software now, or can you wait about 2 1/2 months for CS6 to ship?
2. Are you upgrading from a very old version or starting out fresh with Adobe Creative Suite?
Another thing to consider is whether or not you're interested in the Adobe Creative Cloud, which is a current service offering but will be coming into full effect with CS6. It will be a subscription service but it looks like it will be an incredible value for the user who typically upgrades with each version and uses the software on a near-daily basis.
If you need/want a box software and don't plan to upgrade again for a long time, then perhaps buying CS5.5 right now while it's 1/2 off is a good deal for you. You might also want to wait until March 1st, because Adobe has a 30 day return policy and you may want/need to consider that as an option if a bunch of new buzz builds about CS6. Also, sometimes early March has been a cutoff date for free upgrades to the next version when it's released in April (again, this is based on past scenarios...no one will be able to guarantee anything about these considerations).
I typically upgrade for each full version, which has run me about $500-$700 on average each time (from CS2 to CS3, then CS4 and now CS5). I did not upgrade to CS5.5 because I didn't really need to, so my cost for CS5 has been about $25 per month for the past 2 years (but without an upgrade to CS5.5). The Creative Cloud, which is slated to start at $49 (whatever that means), looks to include a LOT more stuff and be a reasonable option for my type of usage, so I'm waiting to see how that turns out.