With Windows Azure just around the corner, Amazon figured it was time to blink and cut prices on its core EC2 cloud services.

Starting November 1 all Linux-based on-demand EC2 compute instances will cost 15% than they have.

Amazon say that means that a Small Standard Linux-based instance, say, will run 8.5 cents an hour of computing, not the current 10 cents an hour.

And it's taken a nip here and tuck there in its Windows pricing - but not as much as with its Linux instances - and brought them in line with Microsoft's Azure pricing of 12 cents an hour for a small instance. Reserved instances appear to be unaffected.

Amazon has also added a MySQL-based hosted Relational Database Service that will compete with the SQL Azure Database and a couple of EC2 High-Memory Instances.

Amazon RDS, currently a public beta and only in the US, is supposed to make it easy and "pain-free" to set up, operate and scale relational databases in the cloud, providing resizable capacity while automating administration tasks such as setup and provisioning, patch management, and backup - and storing the free backups for a user-defined retention period.

Amazon, of course, already offers the basic SimpleDB as well as SQL Server, Oracle, PostgreSQL, Sybase, and Vertic AMIs.

The RDS service comes in five sizes priced from 11 cents to $3.10 an hour with 5GB-1TB of separately priced storage. It's supposed to scale via an API but Tech Crunch cautions that resource allocation may not automatically grow and scale with resource requirements.

Amazon says its new High-Memory Instances expand the computing configurations available for EC2 as far as CPU capacity, memory resources and networking throughput go. They're designed for memory-intensive workloads such as databases, caching and rendering, and optimized for low-latency, high-throughput performance.

There are two of them: a plainly labeled Double Extra Large consisting of 34.2GB of memory, 13 ECU (four virtual cores with 3.25 ECU each), 850GB of storage and a 64-bit platform and an equally plainly labeled Quadruple Extra Large with 68.4GB of memory, 26 ECU (eight virtual cores with 3.25 ECU each), 1690GB of storage and again a 64-bit platform.

The Double Extra Large will run $1.20 an hour for Linux/Unix instances and $1.44 an hour for Windows and the Quadruple Extra Large $2.40 an hour for Linux/Unix and $2.88 an hour for Windows.