I doubt they are stackable since they are web-managed only. I know the Cisco 3750 series is stackable and man is it great. I have several 8 switch stacks that are working wonderfully. Nice to only have to program and remember one IP address.
Netgear have a bunch of web-managed stackable switches. Unfortunately they all have fans, even their 24-port models.
We're probably going to go with the Procurve 1800 even if they aren't stackable as they've got really good reviews (somewhere in the bullet proof range apparently) and we only need the 48 ports for if we expand again, at which point we could simply purchase a 48-port switch. Just would have been nice to only have to buy another 24-port switch.
I specified and installed a 2510-24 and am very pleased. It has 10/100 to the desktops, and a 10/10/1000 gigabit uplink to our main switch. Actual power consumption (thus actual heat) is roughly half the spec, and it is indeed fanless, and indeed has a "forever" warranty: http://www.obviously.com/tech_tips/Switch_Power_Consump...
The 2510 appears to be both manageable via a web page, and via SNMP.