Gmail will increase the free storage gradually in the next days. On October 23, you'll get 4321 MB of storage, then the growth will slow down until January 4, when you'll have 6283 MB of storage. From January 4, you'll receive 3.3 MB every day, that's 10 times bigger than the current rate of growth.
Another good news is that Google Apps mail accounts will have the same quota as standard Gmail accounts, while Google Apps Premier Edition will have 25 GB mail accounts. Previously, Google Apps accounts had 2 GB of storage, while the business edition offered 10 GB per account.
Gmail didn't abandon the paid storage option, but you'll get around 50% more storage for the same price: 10 GB for $20/year, 40 GB for $75/year, 150 GB for $250/year and 400 GB for $500/year. The paid storage will probably become more attractive when Google adds more services, like Google Docs, JotSpot or GDrive.
"In April 2005, we started increasing Gmail storage as part of our "Infinity+1" storage plan. At that time, we realized we'd never reach infinity, but we promised to keep giving Gmail users more space as we were able," explains the Gmail Blog. Meanwhile, Yahoo and Microsoft also increased the storage (Yahoo even claims to offer "infinite" storage) and Gmail became the top webmail service with the least amount of free storage.