From past briefings with Jonathan Rosenberg, aka Father of SIP, and from the moves of ex Microsofter David Gurle has been making with the likes of Avaya, Cisco, Shortel, all of whom cater to the SMB and Enterprise space, these job reqs further point that Skype is planning to mount an attack up-market. While they do that though, they're be very well served to keep an eye and apply some added effort in the small business market too. Here's why.
Enterprise IT and Security folks are not fans of "new." They want safe. Secure. So while they buy Cisco, Avaya and ShoreTel, they also have a security type who will be far more resistant to change. Smaller market companies are more risk willing. Small business likely already uses Skype and a proof point is Citrix' HiDef Conferencing (a client) which continues to grow as their direct +99 connection via Skype makes for unlimited wideband (hence HiDef) conference calling.
Small business wants bigger business features and are more willing to try new things. Lastly, and most importantly, small business is likely more distributed and less likely to be dependent on the carrier. And the carrier, usually the local exchange carrier (AT&T, Verizon, Qwest) already has the sales relationship with the largest companies while the small guy is less entrenched.
Bigger isn't always better. Sometimes, smaller is faster.