From Bell's website:

In order to continue to ensure a consistently high level of service for all of our customers, Bell may be required to manage its network in such a way that no customer, service or application consumes excessive bandwidth which may impede the use and enjoyment of other customers.
This network management will allow Bell to deliver a consistent and reliable experience to all its customers who use real-time sensitive applications like browsing and instant messaging.
Other providers here in Canada have implemented similar types of measures.
It is important to note that all online applications will continue to be available to our valued customers.

Browsing and instant messaging are "real-time sensitive".  Good to know.

From Bell Canada Enterprise's Annual Report (2007):

With the rapid growth in video and other bandwidth-intensive applications on the Internet, we may need to incur significant capital expenditures to provide additional capacity on our Internet network. We may not be able to recover these costs from customers due to competitors’ short term pricing of comparable Internet services. There is also a risk that our efforts to optimize network performance, as a result of significantly increasing broadband demand, through paced FTTN roll-out, traffic management and rate plan changes, could be unsuccessful and result in an increase in our Internet subscriber churn rate beyond our current expectations thereby adversely affecting achievement of our expected number of Internet subscribers in 2008. This could have an adverse effect on our results of operations.

Factors that could cause actual results to differ materially from our expectations expressed in or implied by our forward-looking statements include: general economic conditions; failure to achieve our business objectives; the intensity of competitive activity and the increase in wireless competitive activity that could result from Industry Canada’s decision to license additional wireless spectrum; our ability to respond to technological changes and rapidly offer new products and services; events affecting the functionality of, and our ability to protect, maintain and replace, our networks, information technology (IT) systems and softwares; labour disruptions; the potential adverse effects on our Internet business of the significant increase in broadband demand; competitive risks related to potential changes in foreign ownership restrictions; events affecting the operations of our service providers operating outside Canada; our ability to raise the capital we need to implement our business plan; the consummation of the Privatization (as defined immediately following this section under Privatization of BCE Inc.) is still subject to a number of terms and conditions including the receipt of regulatory approval, resolution of any appeal filed by the debenture holders which affects the approval of the Bell Canada Enterprises 2007 Annual Report 3 Management’s Discussion and Analysis Arrangement (as defined immediately following this section under Privatization of BCE Inc.), and contractual termination rights; our ability to discontinue certain traditional services as necessary to improve capital and operating efficiencies; regulatory initiatives or proceedings, litigation and changes in laws or regulations; increased regulations banning the use of wireless devices while driving; launch and in-orbit risks of satellites used by Bell ExpressVu Limited Partnership (Bell ExpressVu); increased pension fund contributions; and health concerns about radio frequency emissions from wireless devices. These and other risk factors that could cause actual results to differ materially from ourexpectations expressed in or implied by our forward-looking tatements are discussed throughout this MD&A and, in particular, under Our Competitive Environment, Our Regulatory Environment and Risks that Could Affect Our Business and Results.

Grow Broadband – We will continue to invest in advanced network enhancements, such as the continued deployment of fibre-to-the-node (FTTN) technology, in order to meet increased usage demands in a multi-media rich environment and to improve DSL network performance. FTTN will enable speeds of up to 26 Mbps. In the future, as consumer demand for bandwidth-intensive applications increases, we believe that FTTN bandwidth speeds can be increased to more than 40 Mbps through techniques such as shortening VDSL loop lengths and bonding twisted-pair copper telephone lines. Our objective is to migrate high-speed Internet customers to FTTN based on demand and willingness to pay for more speed. We also aim to develop and launch targeted marketing initiatives to further grow IP connectivity sales among business customers and to more aggressively monetize usage of our broadband networks. At year-end, Bell had deployed 4,828 neighbourhood nodes through its FTTN program.

http://bce.ca/data/documents/BCE_annual_2007_en.pdf