I think in terms of an adoption life cycle... Most technology starts out as bespoke solutions for a particular organisation/need. As an idea becomes more mainstream, companies appear in the space and start offering (often expensive) products to fulfill that needs. As the space becomes better understood and more widely adopted by business the space starts to become commoditised and solutions vendors start to compete on price. As prices drop these solutions/products come within reach of SME's who can then start to adopt them.
An example of this would me relational database technology. Many years ago you would have crafted a data storage solution specifically for your application using fopen() and it's friends (I used to work with a SME ERP solution which began life in the early 80's did just that). When relational databases appeared, they were expensive products only available on a Large Enterprise budget. As the benefits became clear more players entered the market at different price points and serving different niches (compare MS Access, MS SQL Server and Oracle for example). Today the relational database space is fully commoditised, with solutions at a huge range of price points (from expensive to free) and features.
So, what technology is available today to Enterprises, but hasn't been fully commoditised yet, or is too expensive or too hard for a SME to adopt. I'd say things like:
- Business Intelligence - Better information leads to better decisions. BI stuff is often still expensive or bespoke.
- VoIP - Better telecoms facilities at a fraction of the price. Today requires technical knowledge that a SME likely won't have on hand.
- Electronic Data Interchange - Achieve cost savings through electronic exchange of information. Standards exist, but your SME's accounting.ERP package likely doesn't support them, nor possibly do all of their suppliers.
- eCommerce - Reach a larger audience and potentially achieve cost savings by allowing customer self service. Solutions exist, but often require customisation for a specific customer, leading to part-generic part-bespoke solutions.
5 years ago I worked for an ERP solution provider targeting SME's and we were starting to implement various solutions for the above, but only for those who specifically requested them. I'd imagine they're approaching mainstream now.