Bears would, by returning from "all in fiat" to "50/50".

It's not like the bears could use their fiat for food, clothes, cars, utility bills or anything like that. Mt Gox has ensured that bears can only use their fiat to buy one thing: bitcoins!

This interesting thing to note about this news is that according to the graph, Bitstamp didn't really rise, so much as Gox has actually fallen to Bitstamp levels.  I will however say I'm happy to see this, especially given the fact that Bitstamp is currently the only Ripple gateway with any real liquidity.  Unless the rumors of Gox connecting to the Ripple network are true of course.   

How does one invest in Ripple, anyway? I'm nowhere near as sold on it as you are, but it's so cheap I'm willing to take a shot.

Well, since we're really just watching Chartbuddy dance around, I'll indulge you.  

First it's important to note that Ripple is not a currency, it's a global payment network that costs virtually nothing to use. Within this payment network you can use any currency you choose.  USD, EUR, YEN, BTC, LTC, PPC or any other currency there is liquidity for.  I say this because it's important to know what you're investing in.  It's not Bitcoin.  It's a true protocol like http, not a single crypto currency.

Second, there is a built in currency, known as XRP, that you can buy and speculate on the potential rise in value.  It's main function however, is to prevent spam within the network.  I will say in the clearest terms that I think investing in XRP's is extremely risky, so don't invest more than you're willing to lose.  

If you want to buy XRP, you simply need to create a wallet and you can either have someone send you some XRP to activate your account or you can purchase some from Bitstamp.  Once your account is active, you can buy and sell XRP right inside the Ripple client.  (Wallet)  If you've seen people selling XRP in the currency exchange, this is what they are doing.  Buying XRP from Bitcoiners and selling them on the open exchange, within the Ripple client, for great profits.

You're welcome.   

Is Ripple actually gaining any traction as a payment network?

I've yet to see a single business accepting XRP or payment through Ripple network, or hear about any major/regular transaction going through it..

Are there any stats about this out there?

No, there is no liquidity besides Bitstamp, basically. No vendors accept XRP for payment. It's basically speculation for XRP only, and it's highly illiquid. XRP is highly prone to manipulation, much more so than BTC. A single entity can easily dump the value of XRP to oblivion. Indeed, a single entity dropped something like 6 million XRP onto the book (selling them 9-10 XRP below spot, mind you), and that alone has caused the value to plummet from mid-70s, now to the 180s.

It's too bad Ripple is tied to Open Coin. As a payment system, it's pretty brilliant and has a lot of potential to be extremely versatile for payments/micropayments. But the supply of XRP is completely fucked, fuck holding it. At the same time, since Ripple has virtually no liquidity, there is really nothing to be done but trade in and out of XRP.

Ripple is a p2p lending network where payments and defaults "ripple" through a chain of trust.  It will be repeatedly abused by scammers until it is abandoned except as possibly an inter-exchange lending network.

XRP is how you pay transaction fees on the Ripple network.