Foundry even went into marketing (who would have thought so ???) They certainly judged their supremacy in ethernet switching made this one advertisement riskless. Nevertheless, Foundry's XMR platform was the 1st densiest ethernet routing platform ever. One could object that features were lacking, but still, they got it first.
Cisco got the message and just announced the Nexus 7000 Series platform:
The Nexus 7000 series looks like a very dense chassis (it can contain 32x10GEth port cards), together with a new OS, NX OS. For once, the chassis includes a cable management solution which is really welcome when you reach those densities on a single chassis.

Now Juniper, finding they were left aside, decided to publish, the same week, on their corporate web, a new series of products: EX3200 , EX4200 , EX8200. The birth of the EX Series is a hudge step forward for Juniper, as they were only known in the past to build (very) expensive, high-quality/end, rolls-type-of Routers only.
Whatever came close to switching at Juniper was their recently issued MX960 Ethernet Routing platform, but nothing that had been designed to switch ethernet Frames as a core activity.
From what can be read on their site, the new EX series range from 1U fixed switch to multi-cards chassis, all running under Juniper's renowned JunOS.
It is common knowledge that Juniper knows a great deal about designing carrier class equipments, and a consistent switching offer, if supported by decent a decent pricing policy, can possibly tempt many network architects in a very near future...

EDIT 2008-02-05
Now it appears that plain Layer2 (i.e. less Layer 3 features in a switch) is getting trendy, Force10 just released their new C-Series, which are actually plain switching chassis, just like Juniper's EX and Cisco's NEXUS 7000 platforms. The product page here displays those new chassis.
Funny to see how we've gone from separate machines to switch packets and route packets, back to full featured L3 Switches, and now back to separating Switching and Routing again. As a parallel, I remember Carriers would never use VLANs in the core, and would route every port in a routing dedicated chassis - some years after, vendors decided that a chassis could and should do both, and decided Metro Ethernet was the new black (mainly when Eth 10G became common). With those new products appearing, it just sounds like we're getting back to the trees - time and vendor case studies will tell and will certainly shed more light on my ignorance.

Now if everyone wants to setup one single chassis in their datacenter suite, I would tend to think that we're only creating Single Points of Failure. The only advantage that I see in such dense chassis is the increased ease of management. I would tend to much prefer Juniper's Virtual Chassis feature, that enables you to treat all of your L2 Switches as a single, virtual, chassis instance - which actually looks way more fault-tolerant.
END EDIT